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Full text of "Kilobaud Microcomputing Magazine (August 1981)"

USA S2.95/DM 9.80 





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OP COMPUTING 1 








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Increase Diskette Storage Eightfold □ Can You Top the Epson MX-80? □ 
The Sorcerer Speaks □ How to Maximize Profits □ Build a Videographic 
System D Coping with an Analog World □ TRS-80 Missile Launcher 



Now! Color for Your 



• • • 




Introducing COLORAMA-50 " 
Percom's SS-50 Bus Color VDG 



Featuring . . . 

• Eleven display formats including 8-color semigraphics, 4- 
color graphics, 2-color high density graphics and 2-color 
alphanumerics. 

Moreover, two- and four-color displays may be switched 
between primary and complementary color sets under soft- 
ware control or from the keyboard. 

Full graphic resolutions range from 64 x 64 picture elements 
to 256 x 192 picture elements. 

• Instant display control: The COLOR4MA-50™ is memory 
mapped: your MPU has direct, instant access to display RAM 
and display control registers. 

• Low-cost Modulator Option for Color TV Interface: The 
COLORAMA-50™ provides for installation of an inexpensive 
RF modulator such as Radio Shack PN 277-122 for operation 
using a color TV. 




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SS-50 Bus 
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Nobody supports the 
SS-50 bus like Percom 



SS-50 Bus/Single-Board Computers with I/O ports & 

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Static and Dynamic RAM cards — memory expansion 

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LFD-400/800 1-, 2- and 3-drive mini-disk systems 

Color and monochrome memory-mapped display 

controllers 

Extendable 7-slot SS-50 bus motherboards 

Versatile prototyping boards: SS-50 and SS-30 bus 

Field-proven software: monitors, operating systems, 

drivers, editors, assemblers, debuggers and HLLs. 



Mix in Sound: With the 
optional modulator in- 
stalled, you can comple- 
ment your colorful displays 
with software -controlled audio. 



Introductory 
Price 

$219.95 



• Extended Addressing: The COLOR4A4A-50™ is compatible 
with the SS-50A bus and the extended-address SS-50C bus. 
Map the board into any of the sixteen 64-Kbyte banks of the 
1-Mbyte SS-50C address space. The COLOKAMA-50™ card 
"defaults" to the first (lowest) bank for the SS-50A bus. 

• Cassettee I/O Option: Add a few inexpensive components to 
the on-card circuitry provided and use an audio cassette for 
program/data storage. 

• Provision for On-Card Firmware: Put your display operating 
system, cassette control program, etc. right on the COLOR4- 
MA-50™ card in a 2516 (5-volt 2716) EPROM. Resides in the 
top 2-Kbyte of the card memory space. 

• Operating Software: Included in the comprehensive users 
manual is a listing of a display operating system and cassette 
controller that may be implemented as a callable subroutine 
function from BASIC or existing operating systems. The 
programs are optionally available in a plug-in ROM for 
just $69.95. 

System Requirements 

The COLORAMA-50™ is pin- and outline-compatible with the 
Percom System-50™ bus, the SS-50A (SS-50) bus and the 
SS-50C bus. The composite video-sync signal output will directly 
drive a color (or BW) video monitor. The output may be mod- 
ulated for operation with a standard (NTSC) TV set. A modulator 
is not included. The COLOR/4MA-50™ card occupies 8-Kbytes 
of memory in the upper half of a 64-Kbyte memory space. 
Included on-card is 1-Kbyte of display RAM vvhich will 
accommodate alphanumeric displays, semigraphic displays and 
two low-density full-graphic displays. For the higher density 
graphic displays, additional display RAM is required. The option- 
al RAM ICs may be installed on the card. 



For quality Percom SS-50 bus products, see your nearby 
authorized Percom dealer. To order direct, call toll-free, 
1-800-527-1592. Prices and specifications subject to change without 
notice. Prices do not include shipping and handling. 



PERCOM DATA COMPANY INC 

211 N KIRBY GARLAND TEXAS 7504? 
(214)272 3421 



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™ trademark of Percom Data Company. Inc. 



Most small system users think all micro- 
)mputers are created equal. And they're 
Iht. If you want performance, convenience, 
tyling, high technology and reliability (and 
ho doesn't?) your micro usually has a price 
}g that looks more like a mini. It seems big 
Hlormance always means big bucks. But 
)t so with the SuperBrain! 
Standard SuperBrain features include: twin 
)uble-density 5 1 /4" drives which boast nearly 

1,000 bytes of disk storage - expandable 
10 megabytes. A full 64K of dynamic 
M. A CP/M* Disk Operating System to 
|sure compatibility to literally hundreds of 
jplication packages presently available. And, 
12" non-glare, 24 line by 80 column screen. 



You'll also get a full ASCII keyboard with 
an 18 key numeric pad and individual cursor 
control keys. Twin RS232C serial ports for 
fast and easy connection to a modem or 
printer. Dual Z80 processors which operate 
at 4 MHZ to insure lightning-fast program 
execution. And the list goes on! Feature after 
feature after feature. 

Better yet, the SuperBrain boasts modular 
design to make servicing a snap. A common 
screwdriver is about the only service tool 
you'll ever need. And with the money you'll 
save on purchasing and maintaining the 
SuperBrain, you could almost buy another one. 
For under $3,500, it is truly one of the most 
remarkable microcomputers available anywhere. 



Whether your application is small 
business, scientific, educational or just word 
processing, the SuperBrain is certainly an 
exciting solution to the small computer 
problem. And since you can easily expand it, 
you'll probably never outgrow it. 

Call or write us today for a complimentary 
copy of our "SuperBrain Buyer's Guide." We'll 
show you how you can get big system per- 
formance without having to spend big bucks. 

= NTE2TEC 

Cdata 

= SYSTEMS. .3 

2300 Broad River Rd. Columbia, SC 29210 
(803) 798-9100 TWX: 810-666-2115 





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MICROCOMPUTING 



PUBLISHER/EDITOR 

Wayne Green 

EXECUTIVE VICE PRESIDENT 

Sherry Smythe 

EDITORIAL MANAGER 

Jeff DeTray 

PUBLICATIONS MANAGER 

Edward Ferman 

MANAGING EDITOR 

Dennis Brisson 
ASSISTANT MANAGING EDITOR 

Susan Gross 

COPY EDITOR 

Eric Moloney 

TECHNICAL EDITOR 

Harold Nelson 

EDITORIAL ASSISTANT 

Use Markus 

Linda Stephenson 

Betty Thayer 

ADMINISTRATIVE ASSISTANTS 

Pat Graham, Nancy Noyd 

ASSOCIATE EDITORS 

Robert Baker, Ken Barbier, Frank Derfler, Jr., 
Rod Hallen, Peter Stark, Sherm Wantz 

PRODUCTION MANAGER/PUBLICATIONS 

Nancy Salmon 
ASSISTANT PRODUCTION MANAGER 

Michael Murphy 

ART DIRECTOR 

Diana Shonk 

ADVERTISING GRAPHICS 

Robert Drew, Bruce Hedin, Steve Baldwin, 

Jane Preston 

PRODUCTION DEPARTMENT 

Joan Ahem, Fiona Davies, Linda Drew, Bob 

Dukette, Sandra Dukette, Gary Graham, 

Kenneth Jackson, Ross Kenyon, Theresa 

Ostebo, Dianne Ritson, Deborah Stone, 

Susan Symonds, Thomas Villeneuve, Judi 

Wimberly, Donna Wohlfarth 

PHOTOGRAPHY 

William Heydolph, Terrie Anderson, 

Bill Suttenfield 

TYPESETTING 

Sara Bedell, Michele DesRochers, Stephen 

Jewett, Luann Keddy, Mary Kinzel, Barbara 

Latti, Kelly Smith, Karen Stewart 

CORPORATE CONTROLLER 

Charles Garniss, Jr. 

EXECUTIVE ASSISTANT 

Leatrice O'Neil 

ACCOUNTING MANAGER 

Knud Keller 

CIRCULATION MANAGER 

Debra Boudrieau 
CIRCULATION 

Doris Day, Pauline Johnstone, 
Dion Owens, designer 

BULK SALES MANAGER 

Ginnie Boudrieau 

ASSISTANT TO THE PRESIDENT 

Matthew Smith 

ADVERTISING 

603-924-7138 

Kevin Rushalko, Mgr. 

Louise Caron, Hal Stephens, 

Marcia Stone 



APPLE 
84 

85 

87 

90 



94 



HO 



116 



128 



The Shiny Apple Harold Nelson 

Atter an inauspicious beginning, the Apple III is finally on-line. 

Apples Grow Well in Dallas TomLukers 

A favorable climate should produce a good crop for Apple. 

TO Tell the Truth David Curtis 

Don't lie to your Apple when this program's running. 

Down by the River R. Deininger, R. Miller, P. Capano 
Use your Apple to monitor water quality. 

Apple tO SelectNC for 83 Cents Charles Behrens 
The price for this interface can't be beat. 

Apple BASIC Prettyprinter Michael Keith 

Don't be a slob when it comes to formatting BASIC listings. 

Time for the Apple David Goss 

Simplify the task of adding timekeeping ability to your Apple. 

The Ten Cent Fix Don Lancaster 

Lets you hear programs as you load the tape. 



BUSINESS 
130 Put Your Micro on Wall Street DexHart 

Keep your portfolio up to date. Part 2. 
158 HOW to Maximize Profits James Burns 

With this TRS-80 program, you can get the most out of your resources. 

HARDWARE PROJECTS 

56 HOW tO Cope With an Analog World Theodore T. Tylaska 
Build a successive approximation register for use in A/D converters. 

VideographiC JoeMartinka 

Build a complete video system with text processing and graphics capability. 

Student-Proof Your Computer Ken Reid 

You sometimes need protection from over-inquisitive minds. 



TRS-80 



60 



151 



Page 48. 




Page 84. 



4 Microcomputing, August 1981 



Contents: August 1981 



Frank Derfier The Epson MX-80: A Tough Act to Follow 

This dot matrix printer sets a high standard of quality. 

Sorcerer Peter Vernon The Sorcerer Speaks 

The Cognivox lets your micro understand what you say and answer you back. 

6800 Phil Hughes TSC Extended BASIC 

Quick, bug-free and well worth the price. 



REVIEWS 
48 

146 
154 



Volume V 
No. 8 



SOFTWARE 

TRS-80 Terry Sunday TRS-80 Launchpad 134 

Micros give a lift to aerospace engineering and save time and money. 

Atari William Coisher An Atari Disassembler 142 

Plunging deep into the heart of the steaming ROM jungle. 

pet R b Nottingham What's the Difference? 152 

Spotting and correcting incorrect data. 

TUTORIAL 
Peter stark Firm Up Your Floppy with 800K 36 

Increases the capacity of your five-inch diskette eightfold. 



Publisher's Remarks-6 

Micro Quiz-8 

PET-pourri-lO 

Computer Blackboard-18 

Dial-up Directory-20 

As the Word Turns-28 

Micro-Scope-30 

Letters to the Editor- 195 

New Products-198 



DEPARTMENTS 

Dealer Directory-207 

New Software-208 

Clubs-214 

Corrections-214 

Classifieds-215 

Calendar-216 

Book Reviews-219 

Perspectives-226 



Page 60. 





-ZZZtm^i-jZ. KVft, 



^ 



Page 134. 



This month's cover: 

What's a working microcomputer on a 
Florida beach doing on the cover of this 
month's issue? Have the editors of Kilo- 
baud Microcomputing stayed out in the 
sun too long? 

No, we aren't recommending that you 
pack your Apple II in with the suntan lo- 
tion, blankets and sand pail and shovel the 
next time you head for the beach. 

This cover photo, which is a dramatic de- 
parture from the workstation setting 
where microcomputers are normally 
found, is the work of nationally known out- 
door and wildlife photographer Ozzic 
Sweet. His credits include cover shots for 
such major publications as Time, News- 
week and Look. And while he has done 
covers for technical and scientific publica- 
tions before, this marks the first time that 
he has worked with a computer as a model. 

We think you'll agree that he brings a 
unique perspective to the world of comput- 
er photography. How better than in a sea- 
shore setting to illustrate the versatility of 
the Apple II "go-anywhere, do-any thing" 
computer? 

We commissioned Ozzie for this special 
Apple issue cover "between innings" of his 
tour this spring of the major league base- 
ball training camps in Florida, where he 
was on assignment for Topps, the baseball 
cards people. 

Besides being a talented photographer 
and creative artist, Ozzie is a prolific shut- 
terbug. One magazine photo editor with 
whom he has worked described him as 
"the Henry Aaron and Babe Ruth of the 
magazine cover business." 

Indeed, he has had over 1700 magazine 
covers published. We here at Kilobaud Mi- 
crocomputing are pleased to be included 
among that number. 

—The Editors 



Kilobaud Microcomputing (ISSN 0192-4575) is published 
monthly by Wayne Green, Inc., 80 Pine St., Peterborough 
NH 03458. Subscription rates in U.S. are $25 for one year 
and $53 for three years. In Canada: $27 for one year only, 
U.S. funds. Foreign subscriptions (surface mail)— $35 for 
one year only, U.S. funds. Foreign air mail subscriptions 
—$62 for one year only, U.S. funds. Canadian Distributor: 
Micron Distributing, 409 Queen St. West, Toronto, Ontar- 
io, Canada M5V 2A5. In Europe, contact: Monika Nedela, 
Markstr. 3, D-7778 Markdorf, W. Germany. South African 
Distributor: KB Microcomputing, PO Box 782815, Sand- 
ton, South Africa 2146. Australian Distributor: Electronic 
Concepts, Attention: Rudi Hoess, 55 Clarence Street, 
Sidney 2000, Australia. Second-class postage paid at Pe- 
terborough NH 03458 and at additional mailing offices. 
Phone: 603-924-3873. Entire contents copyright 1981 by 
Wayne Green, Inc. No part of this publication may be re- 
printed or otherwise reproduced without written permis- 
sion from the publisher. 



Microcomputing, August 1981 5 



PUBLISHER'S REMARKS 

Are Shows 
Worth It? 



By Wayne Green 



Consider 
The Time 

And Expense 



Show Hoopla 

Having just managed to survive an in- 
tensive round of computer shows in the 
spring, I see more of them springing up- 
like mushrooms— this fall. Are these af- 
fairs really worth your trouble and ex- 
pense to attend? 

If you are a dedicated hobbyist and 
want to meet and talk with the people in 
the industry, I can see where you might 
get your five or ten dollars' worth at a 
show. Of course, you'll have to deal most- 
ly with the smaller firms, since the big 
ones have pretty much been ignoring 
shows. 

However, it is not likely that you'll see 
anything new. New equipment is no 
longer rushed into being for a show. Back 
when we had one big show a year, there 
might have been some justification for 
getting a new product ready a few weeks 
early so it could be shown at the show. 
Today, with dozens of shows a year, 
what's the difference? 

Even the largest shows can't bring you 
the variety of merchandise you find ad- 
vertised in one issue of Microcomputing. 

Apple ran a series of small shows this 
last spring, and I assume this will contin- 
ue if the enterprise was successful. Oddly 
enough, I've heard nothing from Apple, 
or from any of the exhibitors, about the 
success of the shows. The Boston Com- 
puter Society recently ran an indepen- 
dent Apple show in Boston. It was very 
small, but certainly successful, drawing 
a good crowd. The first independent 
TRS-80 show in New York was moderate- 
ly successful, although lacking some- 
what in crowds due, I surmise, to mas- 
sively absent advertising and promotion. 

The big show of the year was NCC in 
Chicago. This drew about 80,000, hun- 
dreds of whom were interested in micro- 
computers. This is a show for data pro- 
cessing people; no hobbyists or end users 
wanted. Many of the micro firms exhibit, 
in an attempt to overcome inferiority feel- 
ings, rather than for practical reasons. 

You see, the maxi and even the mini 
people are so condescending about mi- 
cros that many micro firms feel they have 

6 Microcomputing, August 1981 



to exhibit at NCC just to prove they are 
really in the business. The maxi crowd is 
not impressed by these "toy" merchants. 
Just as the Cadillac is America's answer 
to the inferiority complex, so NCC is the 
answer for our field. 

What was really new at NCC this year? 
Little. 

I also go to see the Consumer Electron- 
ics Show (CES) because sometimes in at- 
tendance are a few Japanese firms which 
seem confused about where to exhibit 
computers to reach the American mar- 
ket. Hitachi appeared this year, not sure 
what to do about the American market, 
yet afraid to lose out on it. 

The Japanese Dilemma 

With IBM due to show their new micro- 
computer soon— and similar threats 
from DEC, Digital Group and other mini- 
computer firms— the Japanese are begin- 
ning to panic. They have had some nice 
equipment available, but have not fig- 
ured out how to get into the swing of the 
growth here. Apparently, they have not 
managed to find a consultant to explain 
to them how to enter the American mar- 
ket. 

It is rapidly becoming much more ex- 
pensive to get started here. Today it will 
cost about ten times as much as it would 
have a year ago to get going. By next year 
that entry fee may go up another order of 
magnitude. Soon it is going to tax the re- 
sources of even the enormous Japanese 
corporations to get a significant share of 
the US microcomputer market. 

By the way, the rumors of IBM using 
the S-100 bus were just that . . . rumors. 
Using the S-lOO would have been a very 
shrewd move. An even better move 
would have been TRS-80 compatibility. 

The price of the Japanese indecision is 
high. There is no question that the Amer- 
ican market for small computers is not 
only going to continue to grow, but also 
to escalate, eventually to behemoth pro- 
portions. The key to dominating the 
world market will lie in quantity produc- 
tion for the US market, which is develop- 
ing first. Large-scale production means 
lower prices and faster development of 



new technology, giving the firms in the 
US market a decided worldwide advan- 
tage. Whichever firms dominate the US 
market will probably come to dominate 
the European and Asian markets too, so 
the Japanese have a very serious problem. 

The selling of consumer computers in 
the US is a new field and has baffled the 
Japanese so far. Much of the business is 
being done via Radio Shack stores, where 
they have no entry. Then comes the 2000 
or so computer-specialty stores, many of 
which are underfinanced and difficult to 
deal with. A few tries have been made to 
sell via department stores, discount 
chains, office supply stores and so on, but 
the fact is that getting into the American 
consumer-computer market requires 
some very creative thinking, something 
we have not seen in abundance from 
Japan. 

Complicating the sales problems for 
computer stores is the number of sales- 
man hours to sell a system, and the simi- 
lar number of hours required in after-the- 
sale handholding. Furthermore, there is 
the demand for instant service. Any busi- 
ness buying a computer soon finds that 
everything stops when the computer 
stops, so service is needed in minutes, 
not hours or days. This is a situation 
which has not yet been adequately tack- 
led by any firm. 

One of the reasons I'm interested in 
starting a "college" to train people in mi- 
cros is the incredible need for people for 
our field. We need programmers, sales- 
men, technicians, advertising help, mar- 
keting help and so on. The need is des- 
perate and growing as fast as sales. We 
could use a few thousand people with 
micro backgrounds to help the industry 
grow. We won't get the services we need 
unless we have some way of mass-train- 
ing people. We are having to make do 
with poor service, which is costing more 
and more to buy. 

Software firms have the same problem 
facing hardware firms— dealers interest- 
ed in carrying the product, but without 
the cash to stock it and the facilities to 
sell it. This has seriously slowed the 
growth of software publishers, yet without 
this software, the sale of hardware is in- 



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1981 by Melatronics Corp. 



evitably slowed. It's a Catch-22 situation. 
Instant Software, which is one of the di- 
visions of Wayne Green, Inc., could grow 
much faster if more people could be found 
to make things happen. I'm pressured 
every day with demands for more pro- 
grammers, salesmen, marketing people, 
advertising people, promotions people, 
microcomputer technicians, digital au- 
dio technicians, typesetters, graphics 
artists, copywriters, documentation writ- 
ers and so on. We could easily use 50 
more people in Instant Software (though I 
don't know where we'd put that many!), 
and I'm sure we are not unusual in the in- 
dustry. Most of the people I talk with are 
having the same problem. 

In Plain English 

One of the major problems facing com- 
puter stores in selling systems has been 
the language barrier. Something strange 
happens to computerists when they learn 
about computers — they lose all ability to 
communicate in plain language. 

It is my thesis that there is a serious 
need for a magazine about computers 
which is written and edited in English, 
not computerese. This magazine will be- 
come a fact starting with the October 
1981 premier issue. The idea is to make 
information on the uses of desktop com- 



puters available to businessmen. The 
magazine will concentrate on success 
stories of business applications for our 
small computers. 

By buying a couple more buildings and 
expanding the editorial offices of Wayne 
Green, Inc., we have made room for the 
staff of Desktop Computing. We are still 
looking for more help— space sales help, 
editing, writing, typesetting and so on. 

Naturally we are looking for articles for 
Desktop. They should be double-spaced, 
generously margined and should be writ- 
ten with no computer buzzwords. You 
can do it. Readers will want to know what 
hardware and software systems really 
work, how long it takes to get on line, the 
costs, savings, benefits, problems and so 
on. We'll entertain some disaster reports 
too, but for the most part Desktop will be 
upbeat. 

The businessman of today knows that 
he needs a computer, but doesn't know 
what to get or even how to find out. Desk- 
top will bring him this information, all in 
plain language. 

Readers of Desktop will want to know 
your successes with software, with ac- 
cessories and with various systems. 
They'll want to know how to network 
computers so they can provide distrib- 
uted processing, communications, bulle- 
tin boards and all of the lovely things our 



micros can do. The magazine will not be 
restricted to micros, since the dividing 
line between them and low-end mini- 
computers is a fuzzy one at best. It will be 
aimed at the businessman — small and 
large — letting him know in English what 
is going on with computers. 

I really need your help in getting arti- 
cles, subscribers and advertising. In re- 
turn, I think I will be able to help the 
whole computer industry to grow and 
surmount the cash and people problems 
now slowing it down.D 



MICRO QUIZ 



What Does This Program Do? 

When the following program is executed, 

what will be printed? (If there are any 

embedded blanks in the string which is 

printed, replace each blank by the letter b 

with a slash through it: to.) 

A$ = "NECSL" 

B$ = left$(right$(A$.3),2) 

C$ = mid$(A$,2,2) 

B$ = C$ + B$ 

print B$ 

(answer on page 21 7) 



Why Do Professionals Prefer 



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Software from Cybernetics? 



RM/COBOL— The new standard for microcomputer COBOL!! The only COBOL 
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TRS-80 4 . Model II CP/M— The fastest Mod II CP/M with the most features. Out- 
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Plus existing CBASIC2 packages 

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8 Microcomputing, August 1981 



2S252* 



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har >aea r * ne 0f thef? inst the 



2*0*11?*' 



O/s/f; 






Hi.R e ' w ' to the 



*/-, 






A har dc/? 9 lo a Z er (*/ 



I'm just finishing the 

update to my 144 page 

catalog and these are jusi 

a sample of the Rainbow 

of Applications we have 

for your Apple* 
Computer. 



SSSUnx 

Sssssss: 

actj0 n game that * mQst 

DOS 3.2 I 5 5 



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00 



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Atten tvp«o°" lr , nv oos... 

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RAINBOW COMPUTING INC. 



A 



/// 



Our catalog contains 
many more products for 
your Apple computer. 
Please request a free 
catalog with any pur- 
chase, if you only want a 
copy of our catalog at 
this time, please send 
$2.00 for shipping. 
Thank you. 

tf cippkz computer inc. 

•Apple is the registered trademark of Apple 
Computer inc. 

Open Tues - Frl 



Mail Order Dept. No. KB11 • 19517 Business Center Dr. • Northrldge, CA 91324 • Phone orders only (Need Mastercard or Visa) 
U.S.A. (except Calif.) (800) 423-5441 • calif, and Foreign (213) 349-0300 • For information or technical questions (213) 349-556C 
Add $2.50 U.S./ $10.00 Foreign for shipping • Calif, residents add 6% sales tax. 



Microcomputing, August 1981 9 



PEI-POURR1 



By Robert W. Baker 



Commodore 
Colors NCC 



Introduces 

New 803Z 
Micro-Mainframe 



Unfortunately, I couldn't make it to 
NCC in Chicago last May, but I did re- 
ceive several new product announce- 
ments from Commodore. For those that 
haven't heard, a few new goodies are on 
the way that should create quite a stir. 
Pricing and availability were to have 
been announced at NCC, so watch for fur- 
ther details. 



A Color 8032! 

First of all, Commodore has announced 
a color version of their 80-column 8032 
system. The new color 8032 has a high- 
resolution, direct drive RGB (red, green, 
blue) color monitor. It is supposed to pro- 
vide a crisp, easy-to-read display in both 
text and graphics modes. 

Normally, the color 8032 system dis- 
plays green characters on a black back- 
ground, just like the regular 8032. Using 
the control key, the user can then display 
information on the screen using a variety 
of foreground and background color com- 
binations. You can even use reverse field 
with colors for highlighting. Color dis- 
plays can be generated character-by- 
character, either directly by the user, or 
under program control from within a sin- 
gle print statement. 

In all, there are eight colors (black, 
blue, green, cyan, red, magenta, yellow 
and white) available for the background 
color and foreground display. This gives 
you 64 possible combinations in each of 
the three character modes (text, graphics 
and plot). In the graphics mode there's a 
160 x 100 point resolution for creating a 
high-resolution display. 

You should be able to run all software 
developed for the standard CBM 8032 on 
the color version without modification. 
Fortunately, the standard CBM version 
4.0 BASIC interpreter remains un- 



Address correspondence to Robert W. 
Baker. 15 Windsor Drive. Atco. NJ 08004. 




Commodore's new CBM 8032 color microcomputer. 



changed. However, the new color system 
contains an enhanced 32K Screen Edit 
ROM to provide the color handling capa- 
bility. If a program uses any Screen Edit 
routines, it may need some work to run 
on the new color system. 



Micro-Mainframe 

The other new system from Commo- 
dore is their Micro-Mainframe. This is a 
new-generation computer that combines 
the power and languages available on 
mainframe systems with the low cost of 
microcomputers. Applications devel- 
oped on the Micro-Mainframe can be 
transmitted to a mainframe system and 
executed without modification. 

The new computer is based on the 
standard CBM 8032 with the familiar 
12-inch green phosphor display, 73-key 
typewriter-style keyboard, and full cur- 
sor controls. However, the Micro-Main- 



frame is a pseudo 16-bit 6809-based sys- 
tem with 36K ROM, 96K user RAM and 
2K screen RAM ( 134K total). The system 
supports all current CBM peripherals ex- 
cept the C2N cassette recorder. Addition- 
ally, a new communication facility has 
been included to support standard RS- 
232C interfaces with speeds up to 9600 
baud. All files are stored in true ASCII for- 
mat for communication and compatibili- 
ty with mainframe systems. 

An extensive software package for the 
new system has been developed by Wa- 
terloo Computing Systems Limited to 
meet the requirements of the University 
of Waterloo in Waterloo, Ontario, Canada. 
This portable software is particularly 
suited to microcomputers, but identical 
versions are available on medium- and 
large-scale systems. Thus, a user is not 
limited by the capacity of the micro: the 
identical program will run without modi- 
fication on many of the largest and fastest 



10 Microcomputing, August 1981 



^\\/AP1\C\\/APTU ™ 




"FA M^C 

MM M.M mrnKM 



LETTER r 

Lb I I blit 




THE FIRST SUPER-SIMPLE LETTER QUALITY WORD PROCESSOR IN 
THE WORLD THAT CAN SIT NEXT TO YOUR SECRETARY - 

FOR LESS THAN (5,000. 



"Wordsworth™" removes the 
fear and loathing many people have 
about things called "computers" 
and "word processing." Because 
Wordsworth just sits at a desk and 
does what he's told. With unique new, 
simplified software, it can tell its 
typist what to do— step by simple 
step— to perform even the most 
complicated tasks. 

It can not only "take a letter," 
but it can revise it, customize it in mil- 
lions of ways (quite literally), person- 
alize it, print it on your letterhead or 
business form so you can't tell it from 
hand-typed ... in short, everything 
but put it in an envelope. 

Moreover, it can perform all 
sorts of mundane business functions, 



like general ledgers and accounting 
reports, using easily available 
industry-compatible CP/M™ software. 

Installation? Plug it in. (Cable 
supplied.) 

Size? Bigger than a breadbox— 
but not by much. It's about half as big, 
or less, than systems that can't do half 
as much. Definitely desktop— a sub- 
compact 20" by 40". 

Service? Available everywhere. 

Price? About $4, 995. Complete 
and ready to go. 

For the name of your nearest 
dealer — and a free hands-on 
demonstration — just pick up the 
nearest telephone. 

TOLL-FREE 1-600-343-6630. 

In Massachusetts, call collect (617) 828-8150. Telex 951-624. 



LEADING 

edge: 



Leading Edge Products, Inc., 225 Turnpike Street, Canton, Massachusetts 02021 
DEALERS: For immediate delivery from the Leading Edge Inventory Bank™ on "Wordsworth" and other of the 

industry's most popular products, just give us a call. 



^See List of Advertisers on page 194 



Microcomputing, August 1981 11 



systems available. 

The software package consists of inter- 
preters for various languages, an editor, 
an operating system (supervisor) and an 
assembly-language development sys- 
tem. The four language interpreters in- 
clude Waterloo microBASIC, microPas- 
cal, microFORTRAN and microAPL. CO- 
BOL is not yet available, but is under de- 
velopment. These language interpreters 
have been designed specifically for teach- 
ing computer programming. Their de- 
sign emphasizes good error diagnosis 
and debugging capabilities which are 
useful in educational and other program 
development environments. 

Waterloo microBASIC includes ANS 
Minimal BASIC, with certain minor ex- 
ceptions, and several extensions. Such 
things as structured programming con- 
trol, long names for variables, sequential 
and relative file capabilities, integer 
arithmetic, debugging facilities and con- 
venient program entry and editing facili- 
ties have all been included. 

Waterloo microPascal is an extensive 
implementation of Pascal, corresponding 
very closely to draft proposals being pro- 
duced by the ISO Pascal Committee. The 
ISO draft language is a refinement of the 
language originally defined by Wirth, 
varying only in minor aspects. This im- 
plementation includes sophisticated fea- 
tures such as text file support, pointer 
variables and multidimensioned arrays. 
A significant feature of Waterloo micro- 
Pascal is its powerful interactive debug- 
ging facility. 

Waterloo microFORTRAN is a special 
dialect designed for teaching purposes. It 
has many of the characteristics and 
much of the flavor of normal FORTRAN, 
but varies significantly from established 
standards for that language. It has many 
of the important characteristics of the 
WATFIV-S compiler, which is widely 
used on IBM computers, plus some fea- 
tures from the new FORTRAN-77 defini- 
tion. It supports subroutines and func- 
tions, multidimensioned arrays, extend- 
ed character string manipulation, struc- 
tured programming control and file I/O. 
In addition, the interpreter provides a 
powerful interactive debugging facility. 

Waterloo microAPL is intended to be a 
complete and faithful implementation of 
the IBM/ ACM standard for APL with re- 
spect to the syntax and semantics of APL 
statements, operators and primitive 
functions, I/O forms and defined func- 
tions. System commands, system vari- 
ables and system functions are those 
consistent with a single-user environ- 
ment. There are no significant design 
limitations on the rank or shape of arrays 
or name length. The shared variable pro- 
cessor is omitted. Extensions include 
system functions supporting files of APL 
arrays. APL equivalents of BASIC fea- 
tures PEEK, POKE and SYS are also in- 
cluded. 

A text editor known as Waterloo micro- 



EDITOR, which is suitable for creating 
and maintaining both program and 
source data files, is included. It is a tradi- 
tional line-oriented text editor with pow- 
erful text searching and substitution 
commands, including global change. 
Full-screen support and special function 
keys allow text to be altered, inserted and 
deleted on the screen without entering 
commands. Facilities for repeating and 
editing previously issued commands fur- 
ther enhance the usability of the editor. 




HMtWHMNtt 
Muroauiairaaw 



Commodore's new Micro-Mainframe 
combines the power and languages 
available on mainframe systems with 
the low cost of microcomputers. 

Disk-oriented assembler and linker 
programs, the Waterloo 6809 Assembler 
and Linker, are included to support de- 
velopment of general-purpose Motorola 
6809 machine-language programs. The 
Assembler supports syntax and direc- 
tives for Motorola 6809 assembly lan- 
guage and includes powerful macro ca- 
pabilities. In addition, the Assembler 
supports pseudo op codes for structured 
programming control, long names (la- 
bels) and the ability to include definitions 
from separate files. The Assembler pro- 
duces both listings and relocatable object 
files. 

The Linker allows the combination of 
an arbitrary number of relocatable object 
files to produce an absolute loadable and 
executable program file. Since it is disk- 
oriented, the Linker is capable of build- 
ing programs which are larger than the 
RAM work space available. The Linker 
supports building of programs in seg- 
ments or banks for operation in bank- 
switched RAM memory, as well as build- 
ing of programs for operating in normal 
RAM memory. 

The Waterloo microSUPERVISOR is 
an operating system designed for single- 
user microcomputer environments. It in- 
cludes a monitor, library and serial line 
communication support. The Monitor 
program supports loading of Linker-pro- 
duced program files into bank-switched 
RAM memory or normal RAM memory. 
It also provides facilities which are useful 
for debugging machine-language pro- 
grams. There are commands to display 



or alter RAM memory and 6809 registers, 
using full-screen features for ease of use. 
In addition, another command permits 
disassembly of 6809 instructions into as- 
sembly-language mnemonics. 

A library of functions and procedures is 
supplied for general use by other pro- 
grams included in the software package. 
The Library includes support functions 
for input/output operations to the key- 
board, screen and peripheral devices. 
Other elements of the library provide 
floating-point arithmetic, fundamental 
trigonometric functions and several gen- 
eral-purpose utility functions. 

A Serial Line Setup program is includ- 
ed which provides selection of program- 
mable characteristics, such as baud rate. 
The program includes support for estab- 
lishing communication with a host com- 
puter, through a serial line, for accessing 
the host's files or peripheral devices. 

Reference manuals, textbooks and in- 
structor's guides are available for each 
software component of the system. The 
system was on display at the NCC show, 
but deliveries are not scheduled till the 
end of the year. 

New Software 

Several new software packages were 
also announced at NCC. Wordcraft 80 is 
Commodore's new word processor pack- 
age for the 80-column systems. It is en- 
tirely different from the familiar Word 
Pro programs, but provides similar re- 
sults. With Wordcraft you can display 
text in the exact form that it will be print- 
ed. Text can be easily edited and the for- 
mat immediately verified on the display, 
without printing the document. In addi- 
tion, page layouts of up to 1 17 characters 
wide by 98 lines deep can be accommo- 
dated by the automatic scrolling of text 
on the screen. Large documents are di- 
vided into chapters, with one chapter at a 
time held in the computer's memory. 

During text entry Wordcraft will not 
break words when the right-hand margin 
is reached; the entire word is moved to 
the next line. Text editing is accom- 
plished by a few simple keystrokes. Stan- 
dard features include character, word 
and paragraph deletion or insertion plus 
block movement of text from one area to 
another. This word processor supports 
character string search and replacement 
within a chapter on the first of all occur- 
rences. Wordcraft also handles tabs, dec- 
imal tabs, multiple levels of indention 
and automatic centering. Tabs and mar- 
gins can be changed anywhere through- 
out the text without disturbing the previ- 
ous settings. Half-line printer movement 
for subscripts and superscripts is also 
supported from within the text. 

Separate paragraphs or sections of text 
can be easily merged to form finished 
documents. Name and address files, or 
any information, can be merged into a 
standard form letter and then printed. 
The entire process is automatic once the 



12 Microcomputing, August 1981 



Most people just sell disks. 

I sell you a complete system, and then 
I help you make it work. 



It's called support, and it's a rare commodity 
in the microcomputer world. 

It's also one big reason why they call my programs 
"the standard of the industry." 

I'm Irwin Taranto, the one who changed the 
TRS-80* into a serious business computer. When you 
buy my TRS-80 systems (or, for that matter, one of 
my own computers that says "Taranto" on it), you 
buy me. 

You buy my experience in making TRS-80 systems 
work in thousands of businesses around the world. 

You buy the corrections, modifications and 
upgrades I constantly make on my TRS-80 systems. 

And you buy my telephone number. You see, most 
of those thousand businesses needed a little help 
getting their systems up and going, and they called. 
We answered all their questions, and talked them 
through their problems. Every time the questions 
got really tough or really unusual, I'd answer them 
myself, on the phone, right then and there. I still do. 

That pays off in two ways. It makes sure you get 
your systems working. It also alerts me to any little 
operating inefficiencies I might have designed into 
my systems. If there are any general business pro- 
grams anywhere in the world, of any kind, that are 
checked out any better than my TRS-80 systems, 
I'd like to know about them. 




I turned the TRS-80 into a serious computer. 



*A trademark of the Tandy Corporation 



•See List of Advertisers on page 194 



The Model I, II and III business systems. 

So far, I have six systems for the Model I, 
at $99 each: 

Accounts Payable General Ledger 

Accounts Receivable Payroll 

Invoicing Inventory Control 

For the Cash Journal option on the General Ledger, add $50. 

I also have six systems for the Model II : 

General Ledger/Cash Journal $ 299 

Accounts Payable /Purchase Order 349 

Open Accounts Receivable/Invoicing 349 

Additional for Sales Analysis 100 

Balance Forward Accounts Receivable 399 

Payroll, without Job Costing 299 

Additional for Job Costing 100 

Inventory Control 399 

For the Model III, we offer expanded versions 
of the six Model I systems, at $199 each. 

Just call the number below and I'll send you any 
or all of the Model I or Model III systems by return 
mail. If you call about the Model II, I send you 
a questionnaire before I'll send you any systems. 
That lets me individualize the programs to your 
specific applications. 

Why I call them "systems," not "programs!' 

There's a one-word answer: interaction. Each 
of the three sets of programs links to the General 
Ledger, and wherever it's useful, they cross-link 
to each other. For instance, "Sales Analysis" figures 
in a salesman's commission rate, so it links to 
"Payroll." Since it computes profitability within 
product categories, it links to "Invoicing." 

That's what a system is. And that's one big 
difference between the Taranto TRS-80 business 
systems and somebody else's collection of business 
program disks. 

If you like, 111 sell you the hardware, too. 

I offer the TRS-80, Model II, along with selected 
peripherals. If you buy the computer from me, 
you get some extra advantages — hardware that's 
absolutely tailored to the programs, plus even 
more hand-holding from Taranto & Associates. 
The equipment won't cost you any more. 

I can sell you a truly serious, completely supported, 
thoroughly proven business computer system for 
as little as $8000, hardware and software both. 

There's nothing else like it in the market. Believe 
me, it's a far cry from that collection of program 
disks they're selling down the street. 

Taranto 

& ASSOCIATES, INC 

The Total System Store. 

121 Paul Drive, San Rafael CA 94903. 

Outside California, toll free (800) 227-2868. In California, (415) 472-2670. 

Authorized dealers throughout America. 

Microcomputing, August 1981 13 



files and form are set up. 

Any properly interfaced letter-quality 
printer can be used with Wordcraft 80, 
and proportional spacing is supported. 
Single sheet stationery or continuous 
forms can be used. You can specify a sin- 
gle page, chapter or whole document for 
printing. At print time you can also speci- 
fy underlining or heavy printing for those 
text areas so defined. With certain print- 
er interfaces, background printing is al- 
lowed. This means that you can be work- 
ing on one document while another is be- 
ing printed. 

Headers and trailers can be placed on 
each page and changed from chapter to 
chapter. They can even be specified in 
book fashion, alternating for left and 
right-hand pages. Page numbering is 
automatic and the system keeps track of 
all pages, even when a new chapter is 
added or inserted Into a document. 

Included with Wordcraft 80 is a special 
link program that lets the user incorpo- 
rate VislCalc data Into a Wordcraft docu- 
ment. This data can then be edited like a 
standard document. 

Wordcraft 80 is supplied with a com- 
prehensive user's manual, a set of train- 
ing cards and a pocket reference guide. 
The program can store about 350 pages 
of normal text on one standard 8050 disk 
drive. Alternately, a Commodore 4040 




dppkz 



a 



HOT AUGUST BUYS! 

Disk Based System: Apple II or 
Apple II Plus with 48k RAM in- 
stalled, Disk II with controller 
DOS 3.3 $1869 

THE SOURCE® FREE! Buy the 
D.C. Hayes Micromodem II® 
for $379.95 and we'll give you 
The Source ($100 value) Free! 

EPSON MX-70 $399 

Mountain Computer CPS® new 

interface card $199.95 

SMARTERM® 80-column board 

CALL TOLL FREE $299 
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^254 



disk can be used. Retail price for Word- 
craft 80 is listed at $395. 

Another new software package from 
Commodore is a Dow Jones Portfolio 
Management System (PMS). This pack- 
age provides the serious private or profes- 
sional investor immediate access to pric- 
ing and financial information available 
through the facilities of the Dow Jones 
News Retrieval Service and additionally 
functions as an accounting and control 
system for security portfolios. 

The system allows maintenance of 
stock portfolios, automatic valuation of 
positions in the portfolio, retrieval of cur- 
rent and historical quotes and displaying 
and printing of news stories from the pre- 
vious 90 days. This data is available for 
over 6000 stocks and selected news cate- 
gories in the Dow Jones databases. Media 
General Financial Services, a price, divi- 
dend and fundamental financial data- 
base, can also be accessed with this sys- 
tem. 

PMS features easy-to-use screen data 
entry for buys, sells and cash transac- 
tions. A complete year-to-date transac- 
tion audit trail and portfolio summary re- 
port are standard. The system provides a 
graphics display of historical prices and a 
printed copy of news stories, historical 
prices and the graphic displays. 

This software package will run on any 
32K PET/CBM system (2001, 4032, 
8032). A Commodore 4040 or 8050 disk 
and a modem are also required, while a 
4022 printer is supported for optional 
printing. Retail price for this package is 
$149.95. 

The last software package announced, 
Legal Time Accounting, manages the 
business side of a law firm, thus allowing 
lawyers to concentrate on their primary 
task. Specifically, LTA keeps track of cli- 
ent files, matter (case) files and associat- 
ed log entries, which represent services 
performed for individual matters. LTA 
automatically posts log entries to the ap- 
propriate matter and prints individual- 
ized statements according to nine crite- 
ria. A number of options are provided to 
effectively use this information, once en- 
tered into the system. You can easily pro- 
duce a list of clients or matters. 

Client matter inquiry allows viewing 
all open log entries for a particular mat- 
ter. A number of statistics and activity re- 
ports can be produced, including aging 
reports by both lawyer and firm. A utility 
section lets you set up fee and activity 
codes as well as perform normal house- 
keeping functions (such as disk back- 
ups). 

LTA was designed to be easy to use, 
even for those with little or no computer 
experience. Additionally, the system 
closely follows the procedures used in a 
typical law firm. LTA handles about 500 
active clients, 1500 matters and 2500 
open log entries. It was designed for firms 
with up to ten lawyers. The program runs 
on the CBM 8032 with an 8050 disk, and 



will support a 4022 (or similar) printer. 
Retail price is $595. 

VIGIL 

Here's a new and very interesting soft- 
ware package for the PET/CBM from 
Abacus Software. Once I glanced 
through the documentation, I just 
couldn't wait to try it out. VIGIL stands 
for Video Interactive Game Interpretive 
Language. It's an easy-to-learn graphics 
and game language that lets you quickly 
create interactive applications. The lan- 
guage is patterned after the CHIP-8 game 
language available on the RCA COSMAC 
VIP computer, but has much greater ca- 
pabilities. The VIGIL interpreter exe- 
cutes game programs and performs vid- 
eo graphics at much higher speeds than 
normally obtainable with BASIC. 

VIGIL programs are entered and modi- 
fied using the standard BASIC text editor 
built into the PET, the same way as pro- 
gramming in BASIC. If you have a print- 
er, you can even list VIGIL programs just 
like normal BASIC programs. VIGIL was 
designed to read the BASIC text editor 
output stored in memory as its programs, 
just like PET/CBM BASIC. However, be- 
cause of this, a little caution must be used 
in writing VIGIL program statements so 
BASIC keywords are not accidentally cre- 
ated where you don't want them. 

There are more than 60 commands to 
manipulate graphics on the screen with 
80x50 plot positions on a 40-column 
system. It is very easy to display and 
move patterns based on screen coordi- 
nates. Also, testing for pattern collisions 
or hits is easy. For most games, you can 
define standard graphics figures and dis- 
play them anywhere on the screen with 
one simple command. Two registers are 
used to indicate the screen position 
where the pattern will appear. To move 
the pattern you simply issue the same 
command to erase the existing pattern, 
modify the registers containing the dis- 
play coordinates, then issue the com- 
mand again to display the pattern in the 
new screen position. 

VIGIL commands consist of BASIC 
keywords and single-letter or character 
operands. One or more operands identify 
the data or internal registers to be used 
by the command. There are 26 internal 
registers, most of which can be used as 
desired for counters, pointers, etc. Be- 
sides graphics support, commands are 
also included for arithmetic, logical and 
random functions, accessing PET mem- 
ory and loading and executing machine- 
language subroutines. 

Two timers are available under pro- 
gram control. Input commands can read 
the full keyboard or a 4 x 4 portion of the 
numeric keyboard. The parallel user port 
can read joysticks or other attached de- 
vices. VIGIL can also create audio tones 
via the standard user port connection. 
Pitch and duration of the tone are pro- 



14 Microcomputing, August 1981 



gram-controlled and operate simultan- 
eously with screen action. 

The preliminary copy I received was 
very nicely done with good documenta- 
tion. The final package will offer cassette 
versions for the three different ROM sets 
as well as a diskette version. Also, the fi- 
nal manual is supposed to be a 50-page 
printed booklet. Included with each 
package are nine sample programs that 
really help in illustrating how to use 
VIGIL for various types of games. VIGIL 
will sell for $35 in USA and Canada, $40 
elsewhere. 

For more information, write Abacus 
Software, PO Box 7211, Grand Rapids, 
MI 49510. This should really be of inter- 
est if you enjoy writing game programs or 
using graphics. You'll probably never 
want to program another game in BASIC 
after trying VIGIL. 

Kingston KRK-2 

In recent months a number of new 
products for the PET/CBM have been en- 
tering the US from Europe and other 
parts of the globe. One new hardware ad- 
dition is the KRK-2 module from King- 
ston Computers Limited in England. The 
module is really three devices in one: a 
keyboard reset, full keyboard repeat and 
a keyboard clicker. Actually, there is 
even a fourth feature— provisions for 
sound generation. All features are pro- 
vided by a single hardware module but 
operate independently. 

Basically, the KRK-2 package consists 
of a small printed circuit board that con- 
nects between the PET main logic board 
and the keyboard cable. There are no 
modifications to be made to the PET it- 
self. Instead, a rather unique concept is 
used where one IC is removed from its 
socket and then reinserted with a small, 
flexible, printed circuit pad between the 
IC and the socket. The other end of the 
printed pad then connects to the KRK-2 
board. This effectively breaks several 
connections to the IC and routes them 
through the logic on the KRK-2 board. 

Other cables from the module connect 
to the second cassette port for power and 
to a small speaker that is mounted inside 
the PET. All connectors have color-coded 
stickers to aid in matching the correct ca- 
bles. 

New features added by the small mod- 
ule include the RESET function, which is 
activated by holding down the RUN/STOP 
and = keys at the same time. The PET 
will return to the machine-language 
monitor and can be returned to BASIC by 
the X command. The reset function is a 
BASIC "warm" start as previously docu- 
mented in various newsletters and arti- 
cles. It does not destroy your program in 
memory. 

After the reset, you have two options: 
restart your program from scratch or at- 
tempt to continue. To restart, simply en- 
ter a CLR command followed by RUN. 
Details on how to reset the microproces- 



^See List of Advertisers on page 194 



What can you honestly 

expect from an interactive 

data terminal that costs only 

$369?* 






r <* 



/s*l 



***+! . 



ftfelfl 



tUcH 



^ 




« 



J 



""»•, 




Well, to begin with, color graphics. 



yS RCA's VP-3301 has unique color-locking circuitry that gives 
you sharp, jitter-free color graphics and rainbow-free characters. 

Plus much more: Microprocessor control. Resident and 
programmable character set. Reverse video. State-of-the-art 
LSI video control. 20 and 40 character formats. RS232C and 
20 mA current loop. Six baud rates. Eight data formats. ASCII 
encoding. Light-touch flexible-membrane key switches for 
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sor stack and attempt to continue a pro- 
gram are given in the documentation. 

The repeat key function is available 
from the time the PET is first powered on 
when the KRK-2 module is installed. 
There is nothing you have to do to enable 
the function; just hold down any key till it 
repeats. The hardware even provides two 
adjustments to tailor the repeat speed 
and sensitivity to your particular taste. 
The repeat is set up before delivery at a 
reasonably gentle pace so you can enjoy 
the repeat function and yet maintain con- 
tact with the cursor. 

Bear in mind that you must compro- 
mise between something that's ideal for 
joystick-type games but useless for nor- 
mal typing and something ideal for typ- 
ing but boring and slow for games. The 
time delay between holding down a key 
and the start of the repeat action is two 
seconds maximum. 

The key click function can only be acti- 
vated after a POKE 59456,247 is entered. 
Thereafter, the feature can be enabled by 
holding down the RUN/STOP and < keys 
at the same time. It is disabled by holding 
the RUN/STOP and the space bar. Once 
enabled, a simple click sound verifies 
each keystroke for much nicer touch 
typing. 

There are three ways of creating noise 
and/or music under program control 
with the KRK-2 module. The simplest is 
to repeatedly POKE the cassette port at 
location 59456. This is a far cry from 
"music," but can prove useful. 

The second method is by direct control 
of the MICE TRO music generator. A list- 
ing of a very simple program to accom- 
plish this is included in the documenta- 
tion. The form of each note created by the 
music generator is determined by three 
parameters poked in memory prioi to 
calling the routine via an SYS command. 
Two of the parameters determine the 
pitch, while the third determines the 
length of the note (up to four seconds). 

The last method of producing music is 
by using the complete MICE TRO pro- 
gram that is included with the KRK-2 
package. This program provides all the 
interface and control for the simple ma- 
chine-language program provided in the 
manual. It implements an entire lan- 
guage for creating, editing, playing and 
saving music pieces. 

Remember that the methods of gener- 
ating sound via the KRK-2 module are 
not compatible with programs with 
sound written in the US. Most PET own- 
ers use the CB2 line on the user port to 
generate sound with an external speaker 
and/or amplifier. 

As with other products I've seen from 
Kingston, the documentation is excellent 
and the product is first class. The com- 
plete KRK-2 package is $119.50 and is 
available from Microtek, Inc., 9514 Ches- 
peake Drive, San Diego, CA 92123. If you 
are only interested in the keyboard re- 
peat, a KRK-1 module is available for 
$39.95. □ 



16 Microcomputing, August 1981 




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speech synthesizer 

Type-'N-Talk^ an important technological 
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rith an unlimited vocabulary. You can 
mjoy the many features of Type-'N-Talk, ^ 
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r ou operate Type-'N-Talk "by simply typ- 
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r our typewritten words are automatically 
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ie endless uses of 
ipeech synthesis. 

rype-'N-Talk™adds a whole new world of 
speaking roles to your computer. You can 
>rogram verbal reminders to prompt you 
[hrough a complex routine and make your 
:omputer announce events. In teaching, 
|he computer with Type- 'N-Talk '"can 
ictually tell students when they're right 
>r wrong — even praise a correct answer. 

Ld of course, Type-'N-Talk "is great fun 
lor computer games. Your games come to 
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Inglish text is automatically translated 
ito electronically synthesized speech 
rith Type-'N-Talk : M ASCII code from 
rour computer's keyboard is fed to 
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lace to generate synthesized speech. 
ust enter English text and hear the verbal 



response (electronic speech) through your 

audio loud speaker. For example: simply 
type the ASCII characters representing 
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word "hello." 

TYPE- W-TAL.K has its 

own memory. 

Type- 'N-Talk M has its own built-in micro- 
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Place Type-'N-Talk" between a computer 
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on a single data channel. 

Selectable features make 
interfacing versatile. 

Type-'N-Talk ™can be interfaced in several 
ways using special control characters. 
Connect it directly to a computer's serial 
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additional Type-'N-Talk ,v units can be 
connected to the first Type-'N-Talk ) w 
eliminating the need for additional 
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Using unit assignment codes, multiple 
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• 750 character buffer 

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• Selectable data modes for versatile 
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• Baud rate (75-9600) 

• Data echo of ASCII characters 

• Phoneme access modes 

• RS 232C interface 

• Complete programming and installation 
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COMPUTER BLACKBOARD 



By Walter Koetke 



ducat 

R©C©SS 



Something 
For Everyone 
In Minnesota 



You're Not Alone 

The spectrum of educational computer 
applications is already quite large. At one 
end are those who resist all forms of com- 
puter support for a variety of personal 
reasons. At the other end are teachers 
making daily use of Logo in the elemen- 
tary classroom. And there are many edu- 
cators at every definable level between 
these extremes. This article is a collec- 
tion of personal observations on the cur- 
rent state of the microcomputer explo- 
sion and its impact on the precollege 
educational community. 

Last May I attended the annual meet- 
ing of American Educational Data Sys- 
tems (AEDS). As an organization, AEDS' 
interest is all educational applications of 
computer technology. While the organi- 
zation was once completely dominated 
by those interested primarily in ad- 
ministrative applications, the organi- 
zation now focuses on the use of comput- 
ers in instruction. 

The 1981 annual meeting was held in 
Minneapolis, which is the home of the 
Minnesota Educational Computing Con- 
sortium (MECC). MECC (2520 Broadway 
Drive, St. Paul, MN 551 13) produces some 
of today's best instructional software. It 
was featured in the March 1981 issue of 
Creative Computing, which provided a 
comprehensive picture of the organiza- 
tion and much of its available software. 

The AEDS annual meeting was excel- 
lent, with several significant sections for 
anyone interested in instructional ap- 
plications of the computer. The content 
of the meeting overshadowed the incon- 
venience of an older hotel with over- 
crowded and overheated meeting rooms. 
A participant at this meeting almost had 
to be impressed by the diversity of atten- 
dees' backgrounds and job titles. I spoke 
with superintendents, assistant superin- 
tendents, business managers, curricu- 
lum coordinators, directors of computer 
services, department heads, elementary 
and secondary teachers and even mem- 



bers of state education departments. 

This diversity of job titles was exceed- 
ed by the diversity of experience with and 
knowledge of the various aspects of 
computer-supported instruction. I met 
several old friends who've been working 
with computers and kids for over 15 
years. I met several others who still have 
serious doubts about ever allowing com- 
puters to be a part of their instructional 
programs. And you could find attendees 
with every level of computer-related ex- 
perience and nearly every level of per- 
sonal educational philosophy in be- 
tween. No matter what your title and no 
matter what your background, you were 
not alone at the AEDS convention. 

The AEDS meeting program met the 
needs of virtually everyone — and that 
was no small feat. In one section the au- 
dience was shown the printed output of a 
program written by a fifth grader. The 
presenter was very proud that under her 
guidance this rather clever student was 
able to produce a picture of a rocket ship 
and the printed countdown from 10 to 1. 
Audience reaction ranged from, "Wow, 
that's amazing— and he was only in fifth 
grade," to the sound of pencils breaking 
between clenched teeth as those with a 
little more experience fought to remain 
polite and not interrupt the presentation 
of an enthusiastic teacher. 

I nearly chipped a tooth while biting 
my pen during this presentation, as I've 
had the experience of having some of my 
own programs reviewed and then ranked 
with others evaluated by the same review- 
er. Not being selected as the author of the 
best program was no surprise, but dis- 
covering that the "best" program had 
been written by a fourth grader— a fact 
the reviewer still doesn't know— was 
more than a little humbling. 

As more and more students are given 
free access to general-purpose com- 
puters, I suggest most of us shall be both 
pleased and astonished with the result. 
When a student is given a sophisticated 
intellectual tool, he can undertake 



sophisticated intellectual activities once 
thought to be the nearly exclusive do- 
main of those more experienced and 
more educated. 

Another presenter showed us how 
Logo can be used when working with ele- 
mentary school children. As you can 
probably guess, audience reaction 
ranged from, "I've seen the salvation of 
education," to "that guy must be nuts." 
The audience included those who have 
long awaited the commercial availability 
of Logo and those who never before heard 
the word and had no concept of its impli- 
cations for education. 

Certainly the best case for Logo is 
made in Seymour Papert's Mindstorms: 
Children, Computers and Powerful 
Ideas, Basic Books. New York, 1980. I 
consider this to be the most important 
book published for educators in several 
years, and suggest it as required reading 
for all teachers and administrators. 
Papert does not accept the idea that com- 
puters should be used to help us better 
teach those subjects we are already 
teaching. His text addresses the issue 
that computer availability has signifi- 
cantly altered that which should be con- 
tained in a basic education. Computers 
should change what we teach, not just 
how we teach. Do read this book. 

At least one presenter made the case 
for the difficulty of writing educationally 
sound software. Why are these presenta- 
tions always given by someone who 
works for a company who wants to sell 
software to the education market? For 
those who continue to resist the use of 
microcomputers in education, you are 
well advised to look for presentations on 
the high cost of software development. 
You are almost certain to see statistics 
that suggest writing a program will re- 
quire a school district referendum to 

Walter Koetke, Putnam/Northern West- 
chester BOCES, Yorktown Heights, NY 
1 0598. 



18 Microcomputing, August 1981 



allow a new bond issue so the program 
can be paid for after only a few years of 
hardship. 

If you resist the use of microcomputers 
in education, be sure you do not attend 
presentations such as that made by CUE 
(Computer Using Educators). This user 
group offers hundreds of tested, evaluat- 
ed, teacher-developed programs for vir- 
tually nothing. They will trade you their 
disk full of programs for your single origi- 
nal program or sell you any of their many 
disks for $10 each. Efforts such as theirs 
deserve applause and support, and I hope 
similar cooperatives will be established 
elsewhere. You can obtain additional in- 
formation about CUE by writing them in 
care of Don McKell, Independence High 
School, 1776 Education Park Drive, San 
Jose, CA 95133. 

If AEDS were to give an award for 
bravery, my nomination would be the 
presenter of a section that defended the 
recent acquisition of a mainframe time- 
sharing system rather than microcom- 
puters for an instructional environment. 
Certainly there are a few advantages in- 
herent in the larger system, but there are 
also a surprisingly large number of disad- 
vantages. Most important, however, is 
the need for educators to not view micro- 
computers or time-sharing systems as an 
either/or choice. The days of doing every- 
thing with one computer or accessing 
computing facilities in only one way were 
once very real, but they are now no more 
than a page in the history of computing. 

Earl Joseph, a futurist with Sperry- 
Univac, gave presentations that were 
both very enlightening and more than a 
little frightening. Be sure to hear this 
man should you ever see his name on a 
program. As he speaks of the latest tech- 
nological developments permitting the 
production of "teachers on a chip" and 
then "schools on a wafer," he has to have 
the best view in the house as he can see 
the faces of the audience. Some of the au- 
dience appear to be in shock, some 
search desperately for a flaw in his rea- 
soning, some see new hope for the future 
and eagerly take notes, and some just 
cross their fingers and count the years 
until their retirement. 

While his scenarios mean many dif- 
ferent things to the audience, I hear him 
describing the world in which today's 
elementary and even secondary students 
must not just survive, but in which they 
must compete, make a living and raise a 
family. Their environment will be quite 
different from ours, and extraordinarily 
different from that which exists in our 
schools. I hear Earl Joseph and I hear a 
plea that we educate today's students so 
they are able to deal with the very dif- 
ferent world that will be their future. 

AEDS also included several presenta- 
tions on the administrative applications 
of computers. As with topics on instruc- 
tional computing, you could easily find 
the full range of opinions being present- 



ed. There were several who advocated 
that microcomputers can do nearly all 
administrative tasks, and there were a 
few suggesting that the microcomputer 
is inappropriate for any but the most 
trivial administrative support. 

Noteworthy was the fact that all 
presenters who spoke of microcomputers 
spoke of very small hardware configura- 
tions — those that could be purchased for 
$3000 or less. Notably absent were dis- 
cussions of applications being developed 
for machines in the $6000 to $10,000 
range. I find this peculiar, for some of the 
machines in this price range are capable 
of doing all of the administrative process- 
ing for any school district containing less 
than 10,000 pupils. 

Vendor displays at the AEDS meeting 
were, as is often the case, more interest- 
ing between the booths than in front of 
them. Most striking was the fact that 
there was no new hardware and only one 
piece of new software displayed at the 
meeting. Also notable was the absence of 
any mid- to upper-priced microcomputer 
configurations. 

The single new piece of software dis- 
played was Texas Instruments' Logo 
package. Although prototypes have been 
occasionally seen for some time, the Logo 
package is finally available to all of us. I 
consider this a major step forward in the 
application of computer technology to in- 
struction, and certainly a feather in the 
cap of TI as they've taken a nontrivial 
monetary risk in supporting this step. 
The generally poor reviews of the TI 99/4 
microcomputer are well known and well 
founded. However, if you accept the 
premise that the price of a microcom- 
puter can be justified by a single signifi- 
cant application, then the TI 99/4 should 
find many new homes as a Logo ma- 
chine. When used exclusively as a Logo 
machine with students, virtually all of 
the objections on which the poor reviews 
were based become invalid. 

Perhaps my own career in education 
gives me a distorted view of the impor- 
tance of preparation and homework, but I 
find it increasingly difficult to be polite to 
vendors who have no idea whatsoever 
about the status, purpose or even me- 
chanics of using their companies' prod- 
ucts. The vendor displays at AEDS were 
typical in this regard. While I readily 
acknowledge the presence of some well- 
informed, helpful vendors, I was told, "I 
don't know how to load a disk," "Don't 
ask me, I never saw this program 
before," "I don't know anything about 
the books we sell either," "The company 
never tells us anything," "If the catalog 
says so I guess it's true" and other similar 
bits of nonsense far too often. Consider- 
ing the high cost of booth space, salaries 
and expenses that the vendors must sup- 
port, they really ought to make the addi- 
tional effort to put some knowledge be- 
hind the smile that greets you when you 
see their display. 



Keynote Speech 

Lou Wangberg, the Lieutenant Gover- 
nor of Minnesota, was the keynote 
speaker at the AEDS convention. He 
delineated several problems and prom- 
ises of computers in education from a 
position of understanding. He certainly 
left the audience wishing that their own 
state and local politicians could be as well 
informed and supportive. Little wonder 
that Minnesota leads the country in the 
application of computers to instruction. 

Wangberg's presentation developed 
the idea that one of the three characteris- 
tics unique to our country is the concept 
that all children have a right to education 
rather than reserving education as a priv- 
ilege for some. Education has also been 
our country's "great leveler" in that we 
treat some skills as essential for all 
citizens. He expressed some concern that 
computers will "mess-up" this mini- 
mum right by being provided for some 
but not all students. He then discussed 
the necessity of providing all students 
with access to computers as part of their 
public school instruction. 

This concern for the haves and have- 
nots regarding access to computers is 
certainly a valid one, and one that others 
have discussed using different scenarios. 
The small business without computer 
support is not likely to survive in a world 
where the competition has computer 
support. Homes with computer access 
will provide a different learning, employ- 
ment and recreational environment to 
family members than is possible for 
those without such access. While I share 
the concern for the have-nots in educa- 
tion and enthusiastically support provid- 
ing all students with access to computers 
for instruction, I suggest we must be 
aware of yet another situation with 
unclear social consequences. 

When nearly all students do gain ac- 
cess to computers, the individualization 
then possible will highlight the differences 
between students. The very bright stu- 
dents will proceed at a pace that far ex- 
ceeds what they can now do. If true indi- 
vidualization of instruction is possible, 
then providing such instruction will en- 
hance and strengthen the differences be- 
tween individuals rather than reduce 
them, as has been the tradition of public 
education. I suggest this possibility as 
neither advocate nor opponent, but as 
one concerned with the social implica- 
tions of the result. 

The AEDS annual meeting did indeed 
have something for everyone. You 
weren't alone no matter what your per- 
spective or experience. You could find 
others in similar situations, and presen- 
tations aimed directly at you. The 1982 
AEDS annual meeting is in Orlando, Flor- 
ida, on May 10-14. For more information 
about this meeting or AEDS, write them 
at 1201 16th Street NW, Washington, DC 
20036. □ 



Microcomputing, August 1981 19 



DIAL-UP DIRECTORY 



By Frank J. Derfler, Jr. 



A Modem 

With Smarts 



DataComm 

Represented 

AtNCC 



Disconnect that modem and put down 
that phone! This month, you and I are go- 
ing to visit the National Computer Con- 
ference in Chicago. While we're there, 
we're going to see the newest things in 
data communications, including the rev- 
olutionary Hayes Stack Smartmodem, a 
way to make our terminals talk and a de- 
vice to connect 16 remote users to a 
TRS-80 Model II over telephone lines. 

The Scene 

McCormick Place is a huge convention 
hall on Chicago's lakefront. The wind is 
always blowing, but even without the 
wind, the place was a storm of activity. 
The floor displays took up three large 
halls. The displays included music, sing- 
ers, movies and lots of color, hardware, 
talking and walking. It was impossible to 
see the whole show in one day, even if 




The C. Itoh X-IOO breaks the pattern by 
using an M6809 CPU. C. Itoh was partic- 
ularly interested in finding U.S. distrib- 
utors who would use their system in 
special applications. This company has 
been succcessful with a low-price daisy- 
wheel printer. Their hew bit-mapping 
graphics printer did a good job of taking 
a picture right off the screen. 

20 Microcomputing, August 1981 



you stopped for only a moment at every 
interesting display. 

The NCC display floor combines the 
microcomputer industry and the big 
computer industry and ignores the dif- 
ference. Apple and Atari were just down 
the aisle from Xerox and IBM. Judging 
from the offerings of both the micro and 
maxi manufacturers, it is going to be- 
come harder and harder to tell the differ- 
ence. The micro people are coming on 
strong with hard disks and networking 
systems, and the maxi folks are market- 
ing desktop work stations with specifica- 
tions that include dual minifloppies, 64K 
of memory and compatibility with the 
CP/M operating system. 

Companies represented include Apple 
and Cromemco, both with interesting 
displays. The Atari booth was always 
crowded. They had many people from 
the Atari product and development staff 
demonstrating the Atari 800 in many dif- 
ferent uses. 

Ohio Scientific announced its new inte- 
grated business network, IBS-NET, 
which is a distributed processing net- 
work that can interconnect most of OSI's 
computer systems. Future plans call for 
the IBS-NET to interface with other local 
networks such as Ethernet. 




The IF-800 from OKI Electric Industry 
Company is an integrated system with 
a beautiful color display, full keyboard 
and Z-80A able to run under CP/M. The 
standard system includes the double- 
sided double-density drives, color moni- 
tor and an 80-column printer with 
graphics capability. Options include a 
ROM cartridge interface and a light pen. 
The total system, fully loaded, will retail 
for about $8000. 




The Hayes Stack Smartmodem shown alone on the left and with its matching clock 
on the right. This unique modem contains its own microprocessor and needs no spe- 
cial software or bus structure to perform automatic dialing and answering func- 
tions. Seems to be a lot of room in that clock cabinet! 



NEW! TPM* for TRS-80 Model II 
NEW! System/6 Package 

Computer Design Labs 



Z80 Disk Software 



We have acquired the rights to all TDL 
industry. Computer Design Labs will contin 

Software with Manual/Manual Alone 



software (& hardware). TDL software has long had the reputation of being the best in the 
ue to maintain, evolve and add to this superior line of quality software. 

— Carl Galletti and Roger Amidon, owners. 



All off the software below is available on any off the 
following media for operation with a Z80 CPU using 
the CP/M* or similar type disk operating system 
(such as our own TPM*). 

for TRS-80* CP/M (Model I or II) 
for 8" CP/M (soft sectored single density) 
for S 1 /*" CP/M (soft sectored single density) 
for 5 1 /4" North Star CP/M (single density) 
for 5 1 /*" North Star CP/M (double density) 

BASIC I 

A powerful and fast Z80 Basic interpreter with EDIT, 
RENUMBER, TRACE, PRINT USING, assembly language 
subroutine CALL, LOADGO for "chaimng", COPY to 
move text, EXCHANGE, KILL, LINE INPUT, error inter- 
cept, sequential file handling in both ASCII and binary 
formats* and much, much more. It runs in a little over 1 2 
K. An excellent choice for games since the precision 
was limited to 7 digits in order to make it one of the 
fastest around. $49.95/$1 5. 



BASIC II 

Basic I but with 1 2 digit precision to make its power 
available to the business world with only a slight sacrifice 
in speed, StiN runs faster than most other Basics (even 
those with much less precision). $99.95/$15. 

BUSINESS BASIC 

The most powerful Basic for business applications. It 
adds to Basic II with random or sequential disk files in 
either fixed or variable record lengths, si rftultaneous 
access to multiple disk files, PRIVACY command to 
prohibit user access to source code, global editing, 
added math functions, and disk file maintenance capa- 
bility without leaving Basic (list, rename, or delete). 
$179.95/$25. 

ZEDIT 

A character oriented text editor with 26 commands 
and "macro" capability for stringing multiple commands 
together. Included are a complete array of character 
move, add, delete, and display function. $49,957$ 15. 



Z80 Text Editing Language - Not just a text editor. 
Actually a language which allows you to edit text and 
also write, save, and recall programs which manipulate 
text. Commands include conditional branching, subrou- 
tine calls, iteration, block move, expression evaluation, 
and much more. Contains 36 value registers and 10 text 
registers. Be creative! Manipulate text with commands 
you write using Ztel. $79.95/$25. 

TOP 

A Z80 Text Output Processor which will do text 

formatting for manuals, documents, and other word 

processing jobs. Works with any text editor. Does 

Justification, page numbering and headings, spacing, 

centering, and much more! $79.95/$25. 

MACRO I 

A macro assembler which will generate relocateable 
or absolute code for the 8080 or Z80 using standard 
Intel mnemonics plusTDL/Z80 extensions. Functions 
include 14 conditionals, 16 listing controls, 54 pseudo- 
ops, 1 1 arithmetic/logical operations, local and global 
symbols, chaining files, linking capability with optional 
linker, and recursive/ reiterative macros. This assembler 
is so powerful you'll think it is doing all the work for you. It 
actually makes assembly language programming much 
less of an effort and more creative. $79.95/$20. 

MACRO II 

Expands upon Macro I's linking capability (which is 
useful but somewhat limited) thereby being able to take 
full advantage of the optional Linker. Also a time and 
date function has been added and the listing capability 
improved. $99.95/$25. 

LINKER 

How many times have you written the same subroutine 
in each new program? Top notch professional pro- 
grammers compile a library of these subroutines and 
use a Linker to tie them together at assembly time. 
Development time is thus drastically reduced and 
becomes comparable to writing in a high level language 
but with all the speed of assembly language. So, get the 
new CDL Linker and start writing programs in a fraction 
of the time it took before. Linker is compatible with 
Macro I & II as well asTDL/Xitan assemblers version 2.0 
or later. $79.95/$20. 



DEBUG I 

Many programmers give up on writing in assembly 
language even though they know their programs would 
be faster and more powerful. To them assembly language 
seems difficult to understand and follow, as well as 
being a nightmare to debug. Well, not with proper tools 
like Debug I. With Debug I you can easily follow the flow 
of any Z80 or 8080 program. Trace the program one 
step at a time or 1 steps or whatever you like. At each 
step you will be able to see the instruction executed and 
what it did. If desired, modifications can then be made 
before continuing. Ifs all under your control. You can 
even skip displaying a subroutine call and up to seven 
breakpoints can be set during execution. Use of Debug I 
can pay for itself many times over by savi ng you valuable 
debugging time. $79.95/$20. 

DEBUG II 

This is an expanded debugger which has all of the 
features of Debug I plus many more. You can "trap" (i.e. 
trace a program until a set of register, flag, and/or 
memory conditions occur). Also, instructions may be 
entered and executed immediately. This makes it easy 
to learn new instructions by examining registers/memory 
before and after. And a RADIX function allows changing 
between ASCII, binary, decimal, hex, octal, signed 
decimal, or split octal. All these features and more add 
up to give you a very powerful development tool. Both 
Debug I and II must run on a Z80 but will debug both Z80 
and 8080 code. $99.95/$20. 

ZAPPLE 

A Z80 executive and debug monitor. Capable of 
search, ASCII put and display, read and write to I/O 
ports, hex math, breakpoint, execute, move, fill, display, 
read and write in Intel or binary format tape, and more! 
on disk 

APPLE 

8080 version of Zapple 



NEW! TPM now available for TRS-80 Model 

II! 

TPM* 

A NEW Z80 disk operation system! This is not CP/M*. 
It's better! You can still run any program which runs with 
CP/M* but unlike CP/M* this operating system was 
written specif ically for the Z80* and takesfull advantage 
of its extra powerful instruction set. In other words its 
not warmed over 8080 code! Available for TRS-80* 
(Model I or II). Tarbell, Xitan DDDC, SD Sales "VERSA- 
FLOPPY", North Star (SD&DD), and Digital (Micro) 
Systems. $79.95/$25. 



SYSTEM/6 

TPM with utilities, Basic I interpreter, Basic E compiler, 
Macro I assembler, Debug I debugger, and ZEDIT text 
editor. 

Above purchased separately costs $339.75 
Special introductory offer Only $1 79.75 with coupon!! 




I 









iT* $160.00 







m m 



ORDERING INFORMATION 

Visa, Master Charge and C.O.D. O.K. To order call or 
write with the following information. 

1. Name of Product (e.g. Macro I) 

2. Media (e.g. 8" CP/M) 

3. Price and method of payment (e.g. C.O.D.) include 
credit card info, if applicable. 

4. Name, Address and Phone number. 

5. For TPM orders only: I ndicate if f or TRS 80, Tarbell, 
Xitan DDDC, SD Sales (5V or 8"). ICOM (5V4" or 
8"), North Star (single or double density) or Digital 
(Micro) Systems. 

6. N.J. residents add 5% sales tax. 



Manual cost applicable against price of subsequent 
software purchase in any item except for the Osborne 
software. 



For information and tech queries call 



For phone orders ONLY call toll free 

1-800-327-9191 
Ext. 676 

(Except Florida) 



SYSTEM MONITOR BOARD (SMBII) 

A complete I/O board f or S- 1 00 systems. 2 serial ports, 
2 parallel ports, 1 200/2400 baud cassette tape inter- 
face, sockets for 2K of RAM, 3-2708/27 1 6 EPROM's or 
ROM, jump on reset circuitry. Bare board $49.95/$20. 609*599*2 1 4© 

ROM FOR SMB II 

2KX8 masked ROM of Zapple monitor. Includes source 
listing $34.95/$15. 

PAYROLL (source code only) 

The Osborne package. Requires C Basic 2. 
5" disks $124.95 (manual not included) 
8" disks $ 99.95 (manual not included) 
Manual $20.00 

ACCOUNTS PAYABLE/RECEIVABLE 
(source code only) 

By Osborne, Requires C Basic 2 
5" disks $124.95 (manual not included) 
8" $99.95 (manual not included) 
Manual $20.00 

GENERAL LEDGER (source code only) 

By Osborne. Requires C Basic 2 
5" disks $99.95 (manual not included) 
8" disks $99.95 (manual not included) 
Manual $20.00 



Many CDL products are available for licensing to 
OEMs. Write to Carl Galletti with your requirements. 

* Z80 is a trademark of Zilog 

* TRS-80 is a trademark for Radio Shack 

* TPM is a trademark of Computer Design Labs. It is not 
CP/M* 

* CP/M is a trademark of Digital Research 
Prices and specifications subject to change without 
notice. 

DEALER INQUIRIES INVITED. 



C BASIC 2 

Required for Osborne software. $99.95/$20. 




COMPUTER 

DESIGN 

LABS 



*^18 



342 Columbus Avenue 
Trenton, N.J. 08629 



^See List of Advertisers on page 194 



Microcomputing, August 1981 21 




Dominique Smith and Matthew Smith represented Instant Software, Microcomput- 
ing and 80 Microcomputing. By the way, in case you are one of those who "inspect- 
ed" an Instant Software program from the rack and then just walked away with it, 
don 't send it back as defective — you got just what you deserve. The display tapes are 
all blank. 



North Star Computers drew a lot of in- 
terest with their multi-user system allow- 
ing up to five users to share the same sys- 
tem and hard disk. They also introduced 
an N Series of disk drives providing .82 
megabytes of formatted storage per dou- 
ble-sided drive. 

Impressions 

Three things were apparent. First was 
the international nature of the show. 
Many of the attendees were from Ger- 
many, France or Japan. The aisles were a 



babble of languages and sound. There 
were many Japanese exhibitors, most of 
whom had complete hardware systems, 
but needed distributors. This year and 
the next will certainly see the big Jap- 
anese marketing push, but the Japanese 
systems may bear many different name- 
plates when they hit the U.S. markets. 

The second impression was that voice 
synthesis has come of age. Electronic 
voices were calling from several booths. 

Finally, there will certainly be a little 
color in your life sometime soon. Color 








Integral Data Systems demonstrated their very nice color printer. This device uses a 
multi-color ribbon which produces excellent quality. Release? "Maybe Christmas. " 
Price? "Maybe $2000, maybe a little more." 



Adam Osborne (left) was on hand to dis- 
cuss his Osborne I system. This dual- 
drive $1 795 unit could blow the compe- 
tition out of the water, or the small 
screen could make it fall flat. Initial evi- 
dence is that it will be a success. Osborne 
says he is backlogged with orders 
through at least the middle of 1982. A 
straw poll conducted while standing in 
various lines showed a lot of enthusi- 
asm for the system, "even if you have to 
use a bigger monitor in some applica- 
tions." The disk capacity (102K each) 
seemed small to some people, but most 
felt that even if they upgraded to higher 
capacity disks the system would still be 
very attractively priced. 

displays were numerous on new sys- 
tems, and lower-cost color printers seem 
to be emerging. The accompanying pho- 
tos will give you many of the details of the 
displays, but this is a column on data 
communications, so let's see what the 
communicator can use. 

Smartmodem 

It all started with a company called 
D. C. Hayes making internal modems for 
Apple II and S-100 bus systems. They 
have changed their name to Hayes Micro- 
computer Products, Inc., but they still 
make the same integral modems. Now, 
they are launching a new product line of 
unique smart peripheral devices capable 
of interfacing with any computer system. 
The first ship of the line is the Smartmo- 
dem, and she's a beauty (see photo). 

The Smartmodem is an RS-232C de- 
vice. It is not a bus decoding or integral 
system. It does, however, provide all of 
the features of an integral modem (auto 
dial/answer, etc.) without unique soft- 
ware. In fact, the modem is so smart that 
the terminal can be completely dumb 
and still have automatic capability. 

A small Z-8 microprocessor in the 
Smartmodem monitors the ASCII char- 
acters coming from the terminal (or mi- 
crocomputer running a terminal pro- 
gram). It acts as a normal modem, con- 
verting the dc signals to audio tones at up 
to 300 bits per second (bps), until it recog- 



22 Microcomputing, August 1981 




The Japanese companies had many 
systems on display. Often, they were 
looking for U.S. distributors for their 
products. Many U.S. system houses will 
probably market Japanese systems un- 
der their own names. NEC was pushing 
their PC-8000 series system, which fea- 
tures a full-color display, Z-80A 4 MHz 
CPU with CP/M compatibility and a very 
nice full-capability keyboard. Note the 
"lO Unit" expansion interface on the 
left. 

nizes a string of characters pre-set in its 
memory. This command string can tell 
the Smartmodem to auto dial and auto 
answer, or to change such operational 
parameters as dialing speed, pulse or 
tone dialing, number of rings to answer 



on, originate/answer mode and local 
echo. The modem will accept the com- 
mand and send you back a prestored 
acknowledgement. 

In normal operation, the Smartmodem 
comes up in an initial default mode 
which is determined by internal switches. 
You can command the modem to per- 
form any of its functions directly from the 
keyboard. An easy way to do this would 
be to use the features of smart terminal 
programs such as Omniterm, ASCII Ex- 
press or Smart 80, which can prestore 
log-on codes of about 40 characters. 
These "macros" can be automatically 
sent by the selection of one or two keys 
and would be perfect for ordering the 
Smartmodem to auto dial. 

Alternatively, a simple BASIC program 
could be used to shoot the desired char- 
acters out the RS-232C port. But I should 
emphasize that the Smartmodem can 
work with any dumb terminal. The com- 
mands can be quickly and easily entered 
from the keyboard. 

The Smartmodem has a nice operating 
feature in the form of a built-in speaker, 
which lets you listen to the phone line. 
This is particularly useful during the 
dialing process so you can tell if you were 
not connected because of a busy signal or 
an unanswered ring. I usually leave a 
phone off the hook (with the microphone 
element removed) when using a direct- 
connection modem just so I can hear 
what's going on. I personally like to have 
the additional sense of hearing involved 
in the communications exchange — may- 
be that comes from 25 years of amateur 
radio operations. 




The Digital Pathways SLC-l 1 voice synthesizer can store well over 300 complete 
words in ROM. The 6502 CPU and extensive operating system provides this 'smart 
peripheral" with many options such as a list of different things to "say" to different 
people in response to one input. The activation of afire sensor may cause the system 
to dial the fire department and give the address; it can then announce "Fire!" over 
the PA system while dialing the company president to tell him to "Get here quick!" 
The voice quality is excellent. The price is about $2000. 



I wonder, though, how much more in 
the way of smarts would be required for 
the Smartmodem to differentiate be- 
tween a busy signal and a ring? 

The Smartmodem is only the first of a 
line of unconventional peripheral de- 
vices. The photo shows a digital clock 
which mounts under the Smartmodem 
and interfaces with it. It hasn't been offi- 
cially released yet and no one is saying 
what the interfaced system will do, but 
the cabinet is awfully big for just a clock. 
The Smartmodem should be reaching 
dealers right about now. The suggested 
retail price is $279— not bad at all for 
such a unique and versatile device. Con- 
tact Hayes Microcomputer Products, 
Inc.. at 5835 Peachtree Corners East, 
Norcross, GA 30092. 

Talk to Me! 

Several months ago, I wrote that the 
man-machine barrier must be broken. 



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SOFTWARE AUTHORS 
AND VENDORS 

We are looking for programs of quality 
and usefulness for the TRS-80* Color 
Computer and Commodore VIC 20. Of 
particular interest are programs dealing 
with home finance and education. 
Please send documentation and/or sam- 
ple to: 

GENERAL VIDEOTEX CORPORATION 

377 PUTNAM AVENUE 
CAMBRIDGE. MASS. 02 I 39 ^392 

(617)491-3393 

Publishers of the Kussmaul Encyclopedia™ 
' ' So simple even a grownup can use it . "™ 
* TRS-80 is a trademark of Tandy Corp. 
Encyclopedia is a trademark of 
General Videotex Corporation. 



••See List of Advertisers on page 194 



Microcomputing, August 1981 23 




• CHECK*** UTItlTV « 
— ACCOUNT •*•* 



The Votrax Type-'N-Talk is a versatile unit which reads aloud an ASCII string of 
characters. Words are defined as a string of characters separated by a space. A sin- 
gle letter or number bracketed by spaces will be pronounced by its name. An audio 
output on the back side of the unit is provided for feeding a more powerful amplifier. 
RS-232C and power are the only inputs. This smart peripheral devices sells for 
$345. 



We have to develop terminal devices that 
are more user-friendly and less depen- 
dent on CRT displays and typing skills. 
The first cracks in the man-machine bar- 
rier have appeared. The NCC featured 
several voice synthesis and voice recog- 
nition systems. 

The highest-quality speech came from 
a system produced by Digital Pathways 
(see photo); it had complete words stored 
in ROM for the use of the synthesizer. But 
at nearly $2000 in single-unit quantities, 
this device is aimed at commercial uses 
(such as electronic banking). 

The hit of the show was a small $345 
unit from Votrax called Type-'N-Talk (see 
photo). The name says it all. The Type- 
'N-Talk reads ASCII code coming from an 
RS-232C port and pronounces the Eng- 
lish phonemes together to make words. 
The Type-'N-Talk needs no special pro- 
gram running in a computer. It has its 
own internal 6800 microprocessor and 
simply reads aloud the ASCII stream. It 
can be connected to any source of ASCII 
characters using RS-232C signaling. The 
price and ease of use make it almost a toy 
that you can keep around the computer 
room just to impress visitors if you do 
nothing else with it. 

Of course, other things can be done 
with such an easy-to-use speech synthe- 
sizer. It is perfect for computer-assisted 
instruction. The verbal feedback it can 
provide in a training situation is un- 
matched by anything that can be easily 
put on a CRT. It has valuable uses for the 
blind, though some of these uses can be 
limited by the simple throughput speed 
of human speech. 

24 Microcomputing, August 1981 



The synthesizer operates from 70 to 
100 bps. This roughly equals two words a 
second or 120 a minute (an average of 
five bytes per word). The unit has some 
buffering and can accept the data at any 
standard rate up to 9600 bps, but it can 
only pronounce it at about 120 words a 
minute. If you overload the 750 character 
buffer, you will simply lose the data. 

This device could be used by the blind 
to read articles or mail from information 
utilities like The Source and CompuServe 
if the information utilities were instruct- 
ed to transmit short "pages" (perhaps 



Epson America took advantage of the 
show to introduce their new MX- 100 
printer, which is essentially an MX-80 
with the capability of printing up to 233 
columns wide in the compressed mode. 
It has both pressure feed and removable 
tractors and includes Epson's Graftrax 
II graphics package that gives high-reso- 
lution bit image graphics. Retail price is 
under $995. A pressure feed version of 
the MX-80 was also on display. That's 
Chris Rutkowski. marketing manager 
of Epson, about to get his finger stuck in 
the print head. 




The folks at Personal Software kept the crowds happy with a constant demonstra- 
tion of their VisiCalc and other "Visi-" software. 










ows your 
love life? 





A little dull around the edges? 

Routine? Predictable? Boring? Maybe ^| ^ 

all it needs is a little Interlude. Interlude is 

the most stimulating computer game ever conceived. 

It combines a computer interview, an innovative 

programming concept, and a one-of-a-kind manual to 

tum your love life into exciting, adventurous, delicious fun! 



Interlude is: romantic. . . playful. . . outrageous. . . a fantasy. Interlude is: ■ A Bed of Roses (Inter- 
lude #1) ■ Mata Hari (Interlude #49) ■ The Chase (Interlude #7) ■ Rodeo! (Interlude #71) ■ The King and I 
(Interlude #60) ■ Some Enchanted Evening (Interlude #84) ■ Caveman Caper (Interlude #82) ■ From Here 
to Ecstasy (Interlude No. 30) ■ Satin Dreams (Interlude #72). 

More than 100 Interludes are included in the program. Most are described in detail in the accompanying manual, 
but several surprise Interludes are buried in the program awaiting that very 

special time when your interview says you're ready. (When you learn secret r#j-fc-4-.r_ _rr_ m m Jt 1L 
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INTERLUDE, Dept. KB, 10635 Richmond Avenue, Houston, Texas 77042. I'm really ready. Send my Interlude today. 



^235 






Apple II (16K) * TRS-80 (Model 1, 16K) * * 

D Cassette ($18.95) □ Cassette ($18.95) 

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Please enclose your check payable to INTERLUDE 
or complete the charge information: 



MasterCard Bank Code 



CHARGE CUSTOMERS: Order by phone toll-free! 1-800-231-5768 Ext. 306 (Texas: 1-800-392-2348 Ext. 306) 

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*Apple II is a registered trademark of Apple Computers, Inc. **TRS-80 is a registered trademark of Radio Shack, a Tandy Co. 




A communications multiplexer that can 
combine 16 phone lines to connect to 
and share the services of a TRS-80 
Model II. 



ten lines of 60 characters). A page is not 
transmitted until a carriage return ac- 
knowledges that the receiver is ready. 
This would, however, greatly slow down 
the rate of data exchange and greatly in- 
crease the connect time charges. 

Alternatively, this device could be used 
to read information utility files if the data 
was downloaded at full speed, stored in 
local files by a smart terminal program 
and later retransmitted out the RS-232C 
port at a slower baud rate. 

The Type-'N-Talk is beautifully set up 
to do this kind of modem -to- talker switch- 
ing because it has a built-in extension of 
the RS-232C line. You do not have to 
change connectors or have two different 
RS-232C ports. 

The quality and clarity of the 
Type-'N-Talk voice take a few minutes to 
get used to. The device has a frequency 
control which actually lets you fine-tune 
the pitch of the voice to your ear, and that 







Tim handy, tlim. 44 page rtftrincc 

contains a synopsis ol tach instruction 

available for the popular 6b02 CPU 

Mnemonics and machine codes in heita 

decimal format are provided for each 

addressing mode Appendices list 

the instruction set alphabetically by 

assembler mnemonics as well as 

numerically by machine code A 

hexadecimal lo decimal conversion 

chart is included Additional 

•nformation of value to pro 

grammers and designers it 

provided, including a chip 

pin out diagram basic timing 

information and diagrams of 

the basic chip architecture 

The 6502 INSTRUCTION 

HANDBOOK tits comfor 

tably m a shirt or hip pocket 

It serves at a convenient reference for programmers. 

technicians and engineers The guide may be obtained by mail for just 

S? 00 pottpjtd in liaXei Order from 

SCELBI PUBLICATIONS ?0 Hurlbut Street Elmwoed. CT 06110 



NAME (pleas* print all information) 



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The quality and clarity of the 

Type-'N-Talk voice 

take a few minutes to get used to. 



helps. After about three minutes of listen- 
ing. I didn't miss a word. It is very much 
like listening to someone with an accent. 
The machine speaks phonetically, not 
colloquially. You get used to the rhythm 
and phrasing quickly, but you might not 
want to hit someone cold with it; say, 
over a telephone. It is not as good (or ex- 
pensive) as the complete word synthesis 
systems used by the telephone company 
and banking services. But those systems 
are limited to about 300 words in ROM. 
Type-'N-Talk has no limitation. It can 
string together phonemes for anything 
you can type. Quite a machine! Phone 
Votrax at 1-800-521-1350 to order one. 

Together? 

The Hayes Stack Smartmodem and 
the Votrax Type-'N-Talk both represent a 
new breed of intelligent peripherals con- 
taining their own microprocessors and 
operating programs. They need no unique 
software to operate. I wonder if you put 
the two devices on line together, would 
the Smartmodem read its command 
string and reply back through the 
Type-'N-Talk, "By Your Command"? 
The modem could tell you when the 
phone was ringing ("One ringy-dingy, 
two ringy-dingy"). It could tell you when 
it had a carrier ("The tone! The tone!"). 
The list is endless. Mr. Hayes, there was a 
lot of room in that clock cabinet! 

16 to 1 

What was that big box sitting next to 
the TRS-80 in the above photo? Simple- 
it's a communications multiplexer. 



A communications multiplexer is a de- 
vice that combines many communica- 
tions channels into one. Let's say, for in- 
stance, that you wanted to combine 
about 16 phone lines together so they 
could connect to and share the services of 
a TRS-80 Model II. Perhaps you wanted 
to set up a private information network 
for a company or development team, or 
groups of geographically separated farm- 
ers, doctors or librarians. Perhaps you 
were not happy with the one-at-a-time 
service most systems provide. You could 
then use a communications multiplexer 
to answer and combine as many as 16 
phone lines into one. 

The unit on display at NCC was an en- 
gineering model just fresh from the FCC 
certification labs, but a production unit 
should be appearing soon. You had better 
be serious though. The price for the 
16-port unit was said to hover about 
$8000. Oh, by the way, this kind of multi- 
tasking is very difficult to do if you don't 
have a hard disk. 

Tell me 

The world of microcomputer-based 
data communications systems is moving 
quickly. The power of its software and 
the quality of the hardware is maturing. 
If you market or manufacture hardware 
or software of interest to data communi- 
cators, let me know. Drop paper mail to 
PO Box 691. Herndon, VA 22070. and in- 
clude a stamped envelope if you want a 
reply. Send electronic mail to TCB967 on 
The Source, 70003,455 on CompuServe, 
or to the AMRAD CBBS (703) 734-1387.D 




Floppy OF THE FUTURE - a5"MICRO FLOPPYCMSK 




C wNn fd « fcw g» ryrt ty - 



Comptxl tuA t0tmtyi for 

1*90 #jMi thtjl vMtft *JMriM4Mt 
fuwlfcr 



<v»iM*i4*iMtfur*Md 
UttoMtoo mm n mut . 

ftNttoMftrob 







Sony's 3-1/2-inch microfloppy drew a lot of attention. The 3-1/2-inch device can pro- 
vide 435K of storage, but it isn't cheap. \ 



26 Microcomputing, August 1981 



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Name 



TM-12GX Monitors at $179.00 plus 2.75 shipping 
TM-12G Monitors at $159.00 plus 2.75 shipping 
TM-12 Monitors at $139.00 plus 2.75 shipping 




Address 



□ Please send OEM information 
about your low cost custom fit smart 
printers. 
d Check or Money Order enclosed 

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AS THE ¥ORD TURNS 



Name That 
Data Service 



By Eric Maloney 

You Can't 

"Tele-text" 

Without a Scorecard 



Videotex? Videotext? Viewdata? Tele- 
text? The increased interest in informa- 
tion retrieval systems has caused some 
confusion as to what term refers to what 
service. The definitions are used some- 
what interchangeably by many people. 



but for the sake of clarity. Microcomput- 
ing has settled upon the following: 

Videotext is a generic term that refers 
to the transmission of textual material 
via telephone lines or TV signals to your 
TV set or microcomputer. It thus encom- 



10 'COMPNAME - PROGRAM TO INVENT COtfANY I PROOUCT NAMES 

15 'BY JEROME S. MILLER, GRAND RAPIDS, MI 49505 

20 'SUGGESTED BY ARTICLE IN KILOBAUD, JUNE '81, P* 24 

25 'BASED ON ALIEN NAME PROG* PERS. COP. MAG* ll/'79 P. 56 

30 'THIS LISTING IS FOR TRS-80 MOO I TRSOOS 2.3 

40 'DELETE LPRINTS IF YOU DON'T NEED WfflCOPY 

100 DIMA$(26),B*<26) 

110 A♦(l)= ,, C0MPU ,, :A$(2)= , 'TaE ,, :A$(3)= ,, MUL^ ,, :A$(4)= ,, DATA ,, 

120 A$(5)= ,, INTER M :A$(A)="DIGI ,, :A$(7)- ,, AUT0 ,, :A$(8)= ,, UNI ,, 

130 A$(9)= M VIDEO":A$(10)= ,, I^FO ,, :A$(11)= H SO^ ,, :A$(11)= ,, «GA ,, 

140 A$(12)= M ASTR0 ,, :A$(13)= ,, MICRO ,, :A$(15)= ,, 0PTr:A$(16)="DYNA" 

150 A$(17)="PLEXI' , :A$(18)= m R^ ,, :A$(19)= ,, COM m :A$(20)="TED#IO h 

160 A$(21)="C0N n :A$(22)= M FILE ,, :A$(23)="INSTA":A$(24)= ,, «TA M 

170 A$(25)= ,, EL£CTR0":A$(26)="ALPM" 

200 B$(1)= ,, DATA":B$(2)= ,, S0FT M :B$(3)="MICR0 ,, :B$(4)= M RW1 ,, 

210 B$(5)= m NET ,, :B$(6)="C0M ,, :B$(7)="TYPE ,, :B$(8)= ,, TECH h 

220 B$(9)= ,, ^TION":Bi(10)= ,, HRITER":B$(ll)= H GR^HICS" 

230.B$(12)="TEX":Bi(13)="SER^€":B$(14)= M FAX ,, :B$(15)="TEL ,, 

240 B$(16)="TR0NIX":BS(17)="PLUS ,, :BS(18)="C0N ,, :B$(19)= ,, FILE ,, 

250 B$(20)="PLEX ,, :B$(21)= ,, COMP m :B$(22)="FLEX ,, :B$(23)= ,, VIDEO h 

260 B$(24)="LINK":B$(25)="METRICS":Bi(26)="CALC n 

300 as:PRINTTAB(12),"<i> CWffWY & PROOUCT NAMES <i>" 

305 LPRINTC««(32):LPRINTT^(12),"<i> COMPANY K PRODUCT N#€S <i: 

310 PRINT 

320 INPUTHOW MANY NttCS DO YOU M^Tf'JN 

325 LPRINTCH<$(32):LPRINT H H0W MANY NMES DO YOU HANT'IN 

330 CLS: PRINT "HERE WE YOUR"N M NAMES"t PRINT 

335 LffiINTOf*$(32):LPRINT n >€RE WE Y0UR";n;"NA*€S" 

340 FOR 1=1 TO N 

350 GOSUB1000 

360 X$(1)=A$(A) 'SELECT PREFIX 

370 GOSUB1000 

380 Xt(2)=B$(B) 'SELECT SUFFIX 

390 PRINT X$(1HX$(2KLPRINT X$(l)+X$(2) 

400 FORT=lTO100:*£XT 

410 NEXT I 

500 PRINT"TYPE 1 FOR NEW LIST; 2 TO EXIT" 

510 Zf=INKEYi:Z=VAL(Z*> 

520 ONZGOTO 300,540 

530 GOTO 510 

540 CLS:PRINTM64,"BYE BYE, COME BACK AGAIN'" 

550 EM) 

1000 A=RM) ( 26 )JB=RND( 26)1 RETURN 



Listing 1 



passes both viewdata and teletext. 

Videotex is commonly used in place of 
videotext, particularly in Canada, which 
recently hosted the Videotex '81 confer- 
ence. But it also refers to a specific infor- 
mation retrieval system being marketed 
by Radio Shack. The full system consists 
of a TRS-80 Videotex terminal and Video- 
tex software. (To show how confusing 
this can get, the October 1980 issue of 
Radio Shack's TRS-80 Microcomputer 
News refers to the software as Videotext 
in the headline and Videotex in the text.) 

Teletext, according to the book Video- 
text: The Coming Revolution in Home/ 
Office Information Retrieval, is "a one- 
way system, which piggybacks digital 
data on the normal television broadcast 
signal by inserting its messages in un- 
used lines of the vertical interval." The 
user is able to call desired pages with a 
special control keypad. 

Viewdata, says the same book, is an in- 
teractive system using the telephone 
lines and a modem. This shouldn't be 
confused with the Viewdata Corp. of 
America, which is a subsidiary of Knight- 
Ridder Corp. 



A postscript to last month's comments 
on acronyms: 

Keith Alexander of Detroit points out 
that many computerists are getting in 
the habit of capitalizing the language 
Ada, as in ADA. But Ada. like Pascal, is 
the name of a person, and is not an acro- 
nym. Ada Augusta Lovelace was a math- 
ematician, and an associate of Charles 
Babbage, a 19th century inventor. 

Alexander also says that the word 
spool, when referring to timesharing 
tasks, is an acronym for Simultaneous 
Peripheral Output On Line. It's a good ex- 
ample of an acronym falling into com- 
mon use as a word. 



In June, this column offered a simple 
formula by which business executives 
could name new products and com- 
panies. It consisted of two lists— 26 pre- 



28 Microcomputing, August 1981 



fixes and 26 suffixes— which could be 
randomly combined to make 676 possi- 
ble monikers. Well, Jerome S. Miller of 
Grand Rapids. MI, wrote a program for 
the TRS-80 Model I that does the pairing 
automatically. Listing 1 is the program, 
while Sample run 1 gives 40 of the possi- 
ble combinations. 

***** 

Is-this-what-you-really-wanted-to-say 
department: Microcomputing author 
Mark Borgerson, who makes his home in 
Corvallis, OR, was looking through the 
software notes for Hewlett-Packard's 
HP-85 when he ran across this mind- 
twister. 

'This particular note concerned prob- 
lems which might occur when users tried 
to run certain application packs with 
other ROMs plugged into the system. It 
seems that the ROM packs compete for 
memory, resulting in an Out of Memory 
error. The software note explained the 
problem this way: 

'The pacs were designed to operate in 



CO COMPANY & PRODUCT NAMES ■» 

HOW MANY NAMES DO YOU WANT 40 

HERE ARE YOUR 40 NAMES 

TECHNOFAX 

TELETEL 

PLEXIMETRICS 

DATACOM 

PLEXIRAM 

DATACOMP 

INSTATEL 

AUTOFILE 

DYNAMETRICS 

PLEXISERVE 

RAMLINK 

COMSOFT 

TELECOM 

INSTAFAX 

INFOTEL 

CDNTEX 

DIGIVIDEO 

ALPHAFAX 

METALINK 

INFOMETRICS 

METAPLUS 

TECHNOMETRICS 

DATALINK 

AUTOTECH 

CONLINK 

FILEFLEX 

DYNASERVE 

FILECALC 

VIDEOLINK 

MICRORAM 

RAM 

INFOMATION 

PLEXITEL 

INSTASERVE 

METATYPE 

FILETECH 

DYNAPLUS 

FILETYPE 

DYNAVIDEO 

INSTAPLUS 

Sample run 1. 



a particular "typical configuration" so 
that more power could be built into each 
application. This trade-off in power ver- 
sus flexible configuration was deliberate- 
ly made to minimize the capabilities of 
our software for the most number of 
users.' 

"Somehow, I think the marketing peo- 
ple at Hewlett-Packard might object to 
the phrasing in that last sentence." 

***** 

Punctuation is a boogeyman for many 
writers. Some have an almost complete 
aversion to it, while others toss punctua- 
tion marks around like grass seed. In this 
latter category are the comma fetishists, 
who can't march across a typed line with- 
out dropping two or three commas along 
the way. Reading their sentences is like 
climbing a tall ladder — by the time you 
reach the top, you're so exhausted that 
you're no longer interested in the view. 
Here's an example that recently crossed 
the Microcomputing desk: 

"Quite simply. Grow is a BASIC lan- 
guage program, currently available to 
Apple II and Plus II and North Star users, 
that allows you to write, in plain English, 
and with only a few system commands, 
original, one-of-a-kind programs, which 
are contained in nodes, mini-programs 
themselves, linked together as needed to 
make up the entire program." 

Is this any way to treat the eomma?D 



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Microcomputing, August 1981 29 



MICROSCOPE 



Compiled by Eric Maloney 



Micro 
M. D. 



Is There 

A Computer 

In the House? 



Data for Health 

An Apple software package that will 
make health information easily accessi- 
ble to both doctors and their patients is 
being tested in several Montreal clinics. 

Over a dozen programs will provide 
preventive and treatment information on 
such topics as chronic diseases and the 
side effects of medication and general 
health tips. 

The package, developed by Dr. Michel 
Bourque of Montreal's Clinical Research 
Institute, is designed for a $3000 Apple II 
with one disk drive and 48K memory. 
Bourque uses Applesoft BASIC with DOS 
2.3, and has a numeric keyboard from 
Advanced Business Technology. 

The programs, in a question/answer 
format, are for the "naive user," Bourque 
says. "We kept it very simple, so it can be 
used without training." The patient 
chooses a disk with the desired topic. The 
computer records the patient's ques- 
tions, so the doctors can change the data- 
base according to demand. The com- 
puter can also question the user to help 
doctors develop demographic data. 

The database has been compiled by 
five doctors at the institute's Hyperten- 
sion Clinic, and at a research clinic head- 
ed by Dr. Robert Perrault of Montreal's 
Prevost Hospital. 

Perrault is now testing programs that 
will provide sex education and contra- 
ceptive information for adolescent pa- 
tients. The microcomputer is set up in a 
waiting room; Perrault hopes it will en- 
courage patients to ask doctors further 
questions. The Hypertension Clinic is al- 
so using the micro, and its stress pro- 
gram is being tested throughout Quebec. 

30 Microcomputing, August 1981 



Another program, to help the chroni- 
cally ill cope with the secondary effects of 
disease, will be tested in late fall, Perrault 
says. Three groups will be given diet and 
treatment advice: one with the micro- 
computer, another by a specialist and the 
third through biblio-therapy, or reading 
material. The hospital has few people for 
one-to-one counseling, Perrault says, and 
the computer should help to ease the 
pressure. 

Though the system is suitable for both 
clinics and private practitioners, Bour- 
que says it can also be used in such 
public places as shopping malls. Private 
physicians will find the system useful for 
after-hours business. And with addition- 
al software, it could even be converted to 
a computer bulletin board for doctors and 
researchers. 

The $100 operating disk and $30 
database are available from the 
institute's Computer and Biostatics 
Research Centre, 1 10 Pine Ave. W., Mon- 
treal, PQ H2W 1R7. 

Contributed by Betty Thayer, 
Microcomputing staff. 



Down on the Farm 

The growing number of farmers using 
microcomputers has spawned a new 
newsletter— Farm Computer News. 

The newsletter, spun off from Meredith 
Corp.'s Successful Farming magazine, 
made its debut in May, promising "all 
kinds of computer information of interest 
to farmers, farm managers and agribusi- 
ness people." 

The idea for the magazine came after a 
survey showed that at least one percent 
of Successful Farming's 750,000 sub- 



scribers own computers, with another 23 
percent expecting to buy one within six 
years. 

Most of those computers are TRS-80s, 
Apples and Commodores. 

The first issue of FCN included an arti- 
cle on a users group called Agri-Cursors, 
a review of the Microsoft Z-80 card, a 
piece on information retrieval, tips for 
computer buying and the Computer 
Trade Mart. 

Editors Chuck Sommers and Gary Vin- 
cent have an Apple 11+ in the office. 
While they don't do any word processing 
on it, they use the Apple for reviewing 
programs and accessing outside data- 
bases. 

"The unit we bought is very typical of 
what the farmer has," says Sommers. 
"This way we put ourselves in their posi- 
tion." 

He adds that neither he nor Vincent is a 
"computer expert," although he has 
taken some computer courses at a local 
community college. But he says that this 
will let them walk through the same 
problems that their readers are experi- 
encing. 

While Radio Shack has actively pur- 
sued the agriculture market, Sommers 
says that Apple dealers "follow their 
sales more than Radio Shack." 

"Radio Shack said basically. 'Here it is; 
take it or leave it.' Sommers says. 
"They knew what we wanted and that we 
were very interested, but they didn't fol- 
low up on it." 

Most farmers are using their com- 
puters for basic business management 
and accounting applications, Sommers 
says. The software is coming from a 
number of places: software houses, 
universities, independent consultants 



and the farmers themselves. Except for 
financial needs, says Sommers, most 
farming applications are too specific for 
general off-the-shelf programs. 

"VisiCalc has been adapted because 
there hasn't been anything else," he 
says. "It adapts well, but it is by no 
means the final answer." 

Some farmers are using their micros to 
access such information databases as 
Agnet, which provides programs that 
farmers can use on their own systems. 
Other services, such as that of the Green 
Thumb project in Kentucky, offer infor- 
mation on such topics as market, the 
weather and pest control. But Sommers 
says that some kinks still have to be 
worked out before farmers make wide- 
spread use of these services. 

"I know a farmer who's trying to use 
CompuServe, and is finding that it's not 
fast enough," he says. "He can get his in- 
formation faster on the radio." 

Subscriptions to Farm Computer 
News are $40 per year. For more infor- 
mation, write to them at 1716 Locust, 
Des Moines, 1A 50336. 



Jerry Van Dyke, Where Are 
You? 

You '11 never have to look at your auto- 
mobile 's idiot lights again with Copilot, a 
microcomputer that monitors the car's 
systems and tells you over the radio 
when any of them are malfunctioning. 

The soft, female voice — which should 
bring a rush of nostalgia to those who 
fondly remember Ann Southern and "My 
Mother the Car" — prompts you with 
such gentle hints as "Please remember 
your lights" and "Please remember your 
keys." It also lets you know when: 

• The door is not closed tightly. 

• You're almost out of gas. 

• Your brakes are about to fail. 

• Your oil pressure is low. 

• The lights are left on after the engine is 
turned off. 

• The engine is about to overheat. 

• The keys are left in the ignition. 

• The seat belts are left unfastened. 

• The battery voltage is low. 

• Diesel engines are not warmed up. 
Copilot is the creation of Aristotle, Inc., 

owned by brothers John Aristotle and 
Dean Phillips. J. A. also goes by the alias 
The A-Bomb Kid— he's the Princeton Uni- 
versity student of several years ago who 
made news by designing an atomic bomb 
from public documents. He's now 25, 
while his brother, an MIT graduate, is 23. 

Dean says the Copilot is essentially a 
verbal set of idiot lights. The unit taps in- 
to the wires that run to the various lights 
and buzzers in the dash. Each unit, while 
not programmable by the owner, has 
what Phillips calls "a certain amount of 
learning ability," which lets the owner 
adapt it to his particular make of car. 

With the exception of fuel, the critical 
levels at which Copilot responds are pre- 



determined. The owner can adjust the 
computer to warn him or her of low fuel 
at anywhere from empty to half a tank. 
The voice will pipe up whether the radio 
is on or off. 

Why a female voice? "It was a very con- 
scious decision on our part," Phillips 
says. "The noise in a car tends to be low- 
frequency, and a male voice literally gets 
lost. Also, we felt that a female voice was 
more pleasing to hear." 

Phillips says that Copilot is made to fit 
all cars. "If it comes out of Detroit and 
uses standard engine technology, it can 
use our system." It is also usable by 
trucks, buses and most other types of 
vehicles. 

The company claims that Copilot is a 
first in the industry. Datsun has a model 
that talks, but, says Phillips, they use 
"what is literally a small record player." 
General Motors uses a microprocessor in 
some of its Cadillacs, but it does not have 



The soft, female 

voice prompts you 

with such gentle 

hints as "Please 

remember your lights" 

and "Please remember 

your keys." 



voice capability (see next article). 

"Many automobile manufacturers 
didn't think that voice was possible for at 
least a couple of years, so they didn't 
bother with it," Phillips says. 

By the way, if you're a hardware tinker- 
er thinking of buying one to modify for 
other uses, Phillips warns against it. The 
unit uses National Semiconductor's Digi- 
talker DT1050 integrated circuit set, but 
uses special operating software and a 
custom-designed vocabulary. 

The Digitalker kit is available commer- 
cially, and includes a vocabulary of 144 
expressions. For a complete discussion of 
the kit, see Steve Ciarcia's article "Build 
a Low-Cost Speech-Synthesizer Inter- 
face," on page 46 of Byte magazine's 
June 1981 issue. 

Copilot sells for $199.95 plus $4.50 for 
postage and handling. For more informa- 
tion, write Aristotle, Inc., Box 21, Nor- 
walk, CT 06853. If you want to buy one, 
you need to include the make, model and 
year of your car. 

Cadillac Blues 

The microprocessor-controlled 1981 



Cadillacs are beaching like suicidal 
whales, according to an article in Elec- 
tronic Engineering Times. 

In fact, some 100 Cadillac owners in 22 
states have filed a class-action suit 
against General Motors, complaining of 
such problems as stalling in traffic, poor 
fuel economy, engine surges and indeci- 
sive shifting. 

The Cadillac was introduced with 
much fanfare because of its unique 4-6-8 
cylinder mechanism, which uses a 
microprocessor to find the right cylinder 
operation according to the driving cir- 
cumstances. 

An interesting feature of the micro- 
computer, says EET, is that it records 
whether the driver goes over 85 mph. 
The computer will also record whether 
the owner receives proper service within 
30 miles of driving after the Check 
Engine light goes on. 

Time for Beddy-By tes 

Homestead Computer Services, Ltd., of 
Winnipeg, Manitoba, has designed a 
computerized hospital bed monitoring 
system for Winnipeg's Seven Oaks Hos- 
pital. 

Admissions/discharge/transfer (ADT) 
systems have often tied into large com- 
puters to keep track of patient bed use, 
but this is the first microcomputer-based 
bed monitoring system, says Home- 
stead's president Sheldon Fulton. 

The system's speed will let the hospital 
use its bed space more efficiently, saving 
both the hospital and Canadian taxpay- 
ers money. 

The system, in use since Seven Oaks 
opened in January 1981, consists of a 
modified Vector Graphics microcomput- 
er and five G.E. ADS terminals. Current 
patient-status information is stored on 
memory boards which have battery 
backup in case of power failure. 

A terminal is located at nursing sta- 
tions on each of the three floors where in- 
formation can be quickly accessed and 
updated for that floor. Another terminal, 
centrally located at the admitting desk, 
can access and update information for 
the entire hospital. A fifth terminal, 
located in housekeeping, has display 
capabilities only. 

Information provided by the computer 
includes bed status (occupied or empty), 
whether the room is for men or women, 
which wing of the hospital the room is in, 
when the room needs to be cleaned and 
when it's available for admission. 

Florence Landygo, director of health 
records and information services at 
Seven Oaks, has found the system 
helpful and easy to use. Speed of informa- 
tion communication and reduced paper 
flow are two of the advantages of the new 
micro system. "By and large it does its 
job," Landygo says. Two modifications 
she recommends are inclusion of the pa- 
tient's name with the other data dis- 



Microcomputing, August 1981 31 



played on the screen and printout capa- 
bility. 

Although it's too early to tell how much 
money Seven Oaks has saved through 
microcomputer-based bed monitoring. 
Homestead Computer Services is op- 
timistic about the success of such 
systems. Says Fulton, "We're interested 
in seeing where we can go from here." 

Contributed by Lise Markus, 
Microcomputing staff. 



Publications on Courseware 

Several new publications focusing on 
courseware are out, or will soon be avail- 
able. 

School MicroWare Reviews will make 
its debut in July, and will feature reviews 
for some 100 instructional programs and 
packages. The publication, which will 
come out twice a year, will be organized 
by school department and subject. A 
rating of each software package will be 
accompanied by comments on documen- 
tation, instructions to users and the 
student-computer dialog. Each edition 
will also include an index to evaluations 
in other publications. 

SMW Reviews will cost $30 per edition. 
Subscribers to Dresden's other publica- 
tion, the School MicroWare Directory, 
will receive it free if they submit evalua- 



tions to Reviews. Nonsubscribers whose 
reviews are used will receive it for half- 
price. 

Dresden Associates, Inc. is located at 
PO Box 246, Dresden, ME 04342. Call 
207-737-4466 for an evaluation form and 
instructions. 

The 1981 Courseware Market Report, 
published by Shotwell and Associates, is 
billed as "the first comprehensive refer- 
ence book for all individuals, companies, 
and institutions preparing educational 
products for the computer software 
market." 

The report includes statistics on hard- 
ware installations in educational institu- 
tions, a discussion of videodisk technolo- 
gy, a listing of hardware and courseware 
suppliers and a discussion of program- 
ming and authoring languages for devel- 
oping educational software on micro- 
computers. 

Price for the volume is $175. 

Shotwell and Associates is located at 
44 Montgomery St., Suite 505, San Fran- 
cisco, C A 94104. 

Queue provides several directories of 

educational software. Their IV A Educa- 
tional Software catalog is for the Apple, 
Atari and Compucolor, while the IVB 
catalog is for the PET and TRS-80. The 
IVB catalog also includes limited listings 
for the Sinclair, OSI and SOL micros. The 
catalogs are $8.95 each. 



Queue's address is 5 Chapel Hill Drive, 
Fairfield, CT 06432. 

The National Council of Teachers of 
Mathematics has recently published a 
30-page book entitled Guidelines for 
Evaluating Computerized Instructional 
Materials. The book, written for both ex- 
perienced and novice programmers and 
users, discusses how to find promising 
materials without first buying them, how 
to evaluate the software and how to cata- 
log it. 

The book's forms and checklists are 
designed to be computerized for easy 
use, updating and retrieval. 

The Guidelines are $3.75, $3 for NCTM 
members. The Council's address is 1906 
Association Drive. Reston, VA 22091 
(703-620-9840). 



Help Solve a Murder 

The quick summary read "Help Solve 
a Murder!", and many people accessing 
the Nobug Forum -80 Bulletin Board in 
Cleveland probably thought that it was 
from a frustrated game player fishing for 
clues to an adventure program. But if 
they retrieved the full message, they 
were in for a surprise: it was a call for help 
in tracking down equipment taken from 
a computer store during a robbery that 
resulted in the killing of the owners. 



DR. DALEY OFFERS 
SOFTWARE FOR EVERYONE 



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The data base package allows total user 
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Index 99.95 



MAIL 

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This powerful mailing list package fea- 
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$159.95 



For PET or CBM 2000 or 8000 series with 32 K memory please specify your machine configuration. 



^34 



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Hundreds of schools and individuals 
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phone (616) 471-5514 Sunday-Thursday noon to 9 p.m. Eastern 



32 Microcomputing, August 1981 



The message reported how Henry and 
Laverne Rumberger, owners of the ABS 
Computer Services Store in Olympia, 
WA, were killed on Sunday, Feb. 22. It 
followed with a list of the equipment 
stolen, along with serial numbers. The 
equipment included an Apple III, three 
Apple lis, a disk drive, a BMC monitor, a 
Sony TV, a Centronics 737 and an IDS 
Paper Tiger. 

"If you discover any of these items, 
please contact the Olympia police depart- 
ment," the message concluded, along 
with the department's phone number. 

Nobug operator Ray Furlong says that 
he read about the murders in a micro- 
computer magazine, and thought it was 
a good idea to put the information on his 
system. As far as he knows, it's the first 
time a system has been used for that kind 
of message. 

The idea may be a precursor to more 
organized attempts to locate stolen 
equipment. According to a store owner in 
Seattle, WA, the Seattle-Puget Sound 
area has had a rash of burglaries during 
the last year. Dealers are considering 
forming a dealers association, one func- 
tion of which would be to exchange infor- 
mation on hot hardware. 

"Our service center sees a lot of equip- 
ment, and it would be very easy for us to 
match serial numbers as the stuff comes 
in," he says. 



The "Help Solve a Murder!" message 
has been picked up from Nobug and put 
on at least one other system, the Medical 
Forum-80 BBS in Lansing, MI. 



Ancestors on Disk 

Genealogical Computing, a bimonthly 
newsletter for genealogists and comput- 
erists, begins publication this month. 

The newsletter, put out by Data Trans- 
fer Associates, will include a directory of 
genealogy programs for micros, columns 
on how to computerize family research 
records and program reviews. 

Editors Paul and Saralou Andereck 
operate the Family Historians' Forum, a 
free computer bulletin board system for 
genealogists. The Forum, which has 
been on-line since September of 1979, is 
used to exchange family research infor- 
mation. 

Genealogical Computing costs $12. 
DTA's address is 5102 Pommeroy Drive, 
Fairfax, VA 22032. Call 703-978-7561 
from 6 pm to 6 am on weekdays and noon 
to 6 am on weekends and holidays to ac- 
cess the Forum. 



Dow Jones for PETs 

The Dow Jones Portfolio Management 
System, a software package designed for 
accessing its News/Retrieval Service, is 



now available for Commodore microcom- 
puters. 

The system will run on Commodore's 
dual disk microcomputer. Model 
200 1-32K or Model 4032. Buyers will also 
receive a Dow Jones password and one 
hour of free introductory usage. 

The system, developed by Micro Busi- 
ness Systems of Pine Brook, NJ, is for 
private and professional investors, let- 
ting them maintain multiple portfolios 
and continuously track, value, graph and 
research each one. It automatically re- 
trieves price quotations (on a 15-minute 
delay basis) on some 6000 stocks and 
other securities from Dow Jones' com- 
puterized News/Retrieval Service. 

Dow Jones News/Retrieval Service pro- 
vides business news from Dow Jones' do- 
mestic and international news wires, The 
Wall Street Journal and Barron's Na- 
tional Business and Financial Weekly, 
plus company profiles and 10K extracts 
from Disclosure, Inc.. Washington, DC: 
detailed corporate financial information 
from Media General Financial Services, 
Inc., Richmond, Va.; and a weekly eco- 
nomic survey of key economic and mone- 
tary indicators, with commentary and 
analysis, from Money Market Services, 
Inc., of San Francisco, CA. In addition, 
Free Text Search allows users to retrieve 
news stories as far back as June, 1979 by 
keyword search. □ 




PRESTO! A direct mail system 



EPSON not only gives correspondence quality 

printing, but is an ideal label printer. Tell us 

about your computer. We'll furnish the printer, 

interfaces, cables, and the rest, so you will have 

an instant, low-priced, working system. We 

carry all accessories, printheads and ribbons. 





EPSON MX-80 

9x9 Head 
80 Column 



EPSON MX-100 

9x9 Head 

233 Column 

(Under $1,000) 



EPSON MX-70 

5x7 Head 

80 Column 

CUnder $500) 



ASK FOR OUR 

INSTANT DISCOUNT 

From Roy Hawthorne 

Talk To Bill Tokar On 

Applications 



CALL TOLL FREE 
U.S.A. 

1-800-521-2764 

MICHIGAN 
1-800-482-8393 



Remember: 
We are open 
8:30 AM to 
6:00 PM EST 
Monday — Friday 




master charge 

TMl INTtniANK CARD 



No Credit 
Card Penality 



WRITE TO: 

"The Stocking Source" 
24069 Research Drive 
Farmington Hills, Ml 
48024 
313-474-6708 



»^288 



Microcomputing, August 1981 33 



TWELVE STRONG 

HEATH/ZENITH YOUR 



Pick a strong partner 

A computer purchase is the beginning of a long term 
partnership between you and the people you buy from. 
Your ongoing need for software and accessories re- 
quires a partner who will stand by you with a growing 
line of products. And nowhere will you find a more com- 
plete line of hardware, software and accessories than 
at your Heathkit Electronic Center. Here are twelve 
strong reasons to make Heath/Zenith your partner. 

1. The All-in-One Computer 

The heart of the Heath/Zenith line is the stand-alone 
89 Computer. It's a complete system with built-in 5 1 /4-inch 
floppy disk drive, professional keyboard and keypad, 
smart video terminal, two Z80 microprocessors, and 
two RS-232C serial I/O ports. It comes with 16K RAM, 
expandable to 64K. 

2. Peripherals 

These include the popular Heath /Zenith 
19 Smart Video Terminal, loaded with 
professional features. And the 14 Line 
Printer, priced as low as $495. Other 
fck printer brands are on display, 
w including high 
speed, typewriter^ 
quality printers. 





3. Software 

Word processing, includes reliable, easy-to-use 

Zenith Electronic Typing and powerful, full-featured 

WORDSTAR. 

Small Business Programs, feature General Ledger and 

Inventory Control. 

HUG, Heath Users' Group, offers members a library of 

over 500 low-cost programs for home, work or play. 

4. Programming Languages 

For your own custom programs, 
Microsoft languages are 
available in BASIC (compiler 
and interpreter), FORTRAN 
and COBOL 

5. Operating Systems 

Three versatile systems give you the capability to per- 
form your specific tasks. 

CPIM by Digital Research makes your system com- 
patible with thousands of popular CP/M programs. 
UCSD P-System with Pascal is a complete program 
development and execution environment. 
HDOS, Heath Disk Operating System gives you a 
sophisticated, flexible environment for program 
construction, storage and editing. 




* 





6. Utility Software 

Expand the performance range of your computer with 
a broad selection of utility tools, including the best of 
Digital Research and the complete line of innovative 
Softstuff products. 

7. Disk Systems 

The 8-inch Heath /Zenith 47 

Dual Disk System adds over 2 

megabytes of storage to your 

89 Computer. Diskettes are 

standard IBM 3740 format, double-sided, 
double-density. 

The 5V4-inch 87 Dual Disk System adds 
200K bytes of storage to your 89. Both 
disk systems feature read/write protec- 
tion and easy plug-in adaptability. 



8. Self-Study Courses 

Learn at your own pace 
with Programming 
Courses that teach you 
to write and run your own 
programs in Assembly, 
BASIC, Pascal or 
COBOL 

A course on Computer Concepts 
for Small Business gives you 
the understanding to eval- 
uate the ways a computer 
can benefit your business. 

Personal Computing is a 
complete introduction to 
the fundamentals for the 
novice. Every Heathkit/ 
Zenith course is pro- 
fessionally designed 
for easy, step- by- 
step learning. 




%**€ 



J* 




All Heath /Zenith 
Computer Products 
are available completely 
assembled and tested for 
commercial use. Or in easy 
to-build, money-saving kits 




^236 



34 Microcomputing, August 1981 



*0 



EASONS TO MAKE 






9. Expansion Options 

Communicate with the outside world through a Three- 
port El A RS-232C Serial Interface. 

Expand RAM to 64K with easy-to-install expansion 
chips. 

10. Accessories 

Your Heathkit Electronic Center has the 

latest in modems, black-and-white and 
color video monitors, computer furniture 
and a full line of supplies, accessories, books 
and parts. 

No one stands by you like Heath/Zenith 
We help you get your system up and 
running smoothly. Service is avail- 
able from trained technicians, 
over the phone or at one of 56 
Heathkit Electronic Centers. 

12. Value 

Your money buys you more because 
Heath/Zenith prices are among the industry's most 
competitive. Make your own comparison and find out 
how much you can save. 

Complete, integrated computer hardware and soft- 
ware, designed to serve you and to grow with you 
- that's what to look for in a strong partner. And 
with Heath/Zenith you get it all under 

^^^^ one roof. 

All at your 
Heathkit Electronic 
Center 

Pick the store nearest you 
from the list at right. And 
stop in today for a demon- 
stration of the Heath/Zenith 
89 Computer System. If you 
can't get to a store, send 
$1.00 for the latest Heathkit® 
Catalog and the new Zenith 
Data Systems Catalog of 
assembled commercial 
computers. Write to 
Heath Co., Dept. 351-804, 
Benton Harbor, Ml 49022. 



Visit Your Heathkit Electronic Center* 

where Heath /Zenith Products are displayed, sold and serviced. 



PHOENIX, AZ 

2727 W.Indian School Rd. 
602-279-6247 

ANAHEIM, CA 

330 E. Ball Rd. 
714-776-9420 

CAMPBELL, CA 

2350 S. Bascom Ave. 
408-377-8920 

ELCERRIT0.CA 
6000 Potrero Ave. 
415-236-8870 

LA MESA, CA 

8363 Center Dr. 
714-461-0110 

LOS ANGELES, CA 

2309 S. Flower St. 
213-749-0261 

POMONA, CA 

1555 N. Orange Grove Ave. 
714-623-3543 

REDWOOD CITY, CA 

2001 Middlefield Rd 
415-365-8155 

SACRAMENTO, CA 

1860 Fulton Ave. 
916-486-1575 

WOODLAND HILLS, CA 

22504 Ventura Blvd. 
213-883-0531 

DENVER, CO 

5940 W. 38th Ave 
303-422-3408 

AV0N.CT 

395 W. Main St. (Rt. 44) 
203-678-0323 

HIALEAH, FL 

4705 W. 16th Ave 
305-823-2280 

PLANTATION, FL 

7173 W.Broward Blvd. 
305-791-7300 

TAMPA, FL 

4019 W.Hillsborough Ave. 
813-886-2541 

ATLANTA, GA 

5285RoswellRd. 
404-252-4341 

CHICAGO.IL 

3462-66 W.Devon Ave. 
312-583-3920 

D0WNERSGR0VEJL 

224 0gdenAve. 
312-852-1304 



INDIANAPOLIS, 

2112 E. 62nd St. 
317-257-4321 



IN 



MISSION, KS 

5960 Lamar Ave. 
913-362-4486 

LOUISVILLE, KY 

12401 ShelbyvilleRd. 
502-245-7811 

KENNER.LA 

1900 Veterans 
Memorial Hwy. 
504-467-6321 

BALTIMORE, MD 

1713E. JoppaRd. 
301-661-4446 

ROCKVILLE.MD 

5542 Nicholson Lane 
301-881-5420 

PEABODY, MA 

242AndoverSt 
617-531-9330 

WELLESLEY, MA 

165 Worcester Ave. 
617-237-1510 

DETROIT, Ml 

18645 W. Eight Mile Rd 
313-535-6480 

E. DETROIT, Ml 

18149 E. Eight Mile Rd. 
313-772-0416 

HOPKINS, MN 

101 Shady Oak Rd. 
612^938-6371 

ST. PAUL, MN 

1645 White Bear Ave 
612-778-1211 

BRIDGET0N.M0 

3794 McKelvey Rd 
314-291-1850 

OMAHA, NE 

9207 Maple St. 
402-391-2071 

ASBURY PARK, NJ 

1013 State Hwy. 35 
201-775-1231 

FAIR LAWN, N J 

35-07 Broadway (Rt 4) 
201-791-6935 

AMHERST, NY 

3476 Sheridan Dr. 
716-835-3090 

JERICHO, L.I. NY 

15 Jericho Turnpike 
516-334-8181 

ROCHESTER, NY 

937 Jefferson Rd. 
716-424-2560 

N WHITE PLAINS. NY 
7 Reservoir Rd. 
914-761-7690 



i 



CLEVELAND, OH 

28100 Chagrin Blvd. 
216-292-7553 

COLUMBUS, OH 

2500 Morse Rd. 
614-475-7200 

TOLEDO, OH 

48 S. Byrne Rd. 
419-537-1887 

W00DLAWN.0H 

10133 Springfield Pike 
513-771-8850 

OKLAHOMA CITY, OK 

2727 Northwest 

Expressway 

405-848-7593 

FRAZER, PA 

630 Lancaster Pike 
Rt.30) 
15-647-5555 

PHILADELPHIA, PA 

6318 Roosevelt Blvd. 
215-288-0180 

PITTSBURGH, PA 

3482 Wm.Penn Hwy. 
412-824-3564 

WARWICK, Rl 

558 Greenwich Ave. 
401-738-5150 

DALLAS, TX 

2715 Ross Ave 
214-826-4053 

HOUSTON, TX 

1704 W. Loop N 
713-869-5263 

SAN ANTONIO, TX 

7111 Blanco Road 

512-341-8876 

MIDVALE.UT 

58 East 7200 South 

801-566-4626 

ALEXANDRIA, VA 

6201 Richmond Hwy. 
703-765-5515 
VIRGINIA BEACH, VA 

1055 Independence Blvd. 
804-460-0997 

SEATTLE, WA 

505 8th Ave. N 
206-682-2172 

TUKWILA.WA 
15439 53rd Ave. S. 
206-246-5358 

MILWAUKEE, Wl 

5215 W. Fond du Lac 
414-873-8250 

* Units of Veritechnology 
Electronics Corporation in 
the US. 



Prices and specifications subject to change without notice. 



HEATH/ZENITH 



^236 




Your strong partner 



*sSee List of Advertisers on page 194 



Microcomputing, August 1981 35 



Read how this exercise in data storage frugality increases the capacity of your five-inch diskette eightfold. 



Firm Up Your Floppy 

With 800K 



By Peter A. Stark 



It's quite possible to put 800 kilo- 
bytes of data on one five-inch mini- 
floppy diskette, thus rivalling the 1.2 
megabytes or so that can be stored on 
an eight-inch diskette. 

The trick is to use one of the newer 
disk drives such as the model 92 
made by Micro Peripherals, Inc. 
(MPI), which provide twice the num- 
ber of tracks per side, with two sides, 
and at double density. Since a normal 
five-inch diskette can hold slightly 
over 100K, this multiplies that num- 
ber by eight for a total of about 800K. 

Let's take a look at five-inch floppy 
disk drives in general, and then the 
MPI Model 92 in particular. 

Floppy Fundamentals 

The floppy diskette is a disk of plas- 
tic, five inches in diameter, which is 
coated on both sides with a magnetic 
oxide coating such as that used on re- 
cording tapes. 

The disk is enclosed in a rectangu- 
lar, stiff plastic envelope just a bit 
larger than the disk itself. The inside 
of the envelope is covered with a fi- 
ber material smooth enough that the 
disk can rotate within the envelope 
without being scratched. 

In the center of the diskette is a 
round hole slightly over one inch in 
diameter; the plastic envelope in turn 
has a slightly larger hole in the cen- 
ter. When placed into a disk drive, 
the diskette is grabbed by a metal 
hub from one side, and a plastic ex- 
pansion hub from the other; these 



hubs are centered within the large 
hole in the center of the disk, and 
hold the diskette tightly so it can be 
turned. The disk drive has a small 
motor, usually operated from a + 12 
V dc power supply, which turns the 
metal hub and spindle via a plastic 
belt. In operation, the diskette turns 
at five revolutions per second (300 
rpm). 
The rotating speed must be held 

quite close to this value; most disk 
drives have a built-in regulator, pos- 
sibly with a feedback tachometer on 
the spindle which helps keep the 
speed constant. There is usually a set 
of stroboscopic marks on a flywheel. 
These marks appear to stand still 
when viewed in a fluorescent light 
when the spindle is rotating at the 
correct speed. The motor speed regu- 
lator usually has an adjustment to al- 
low slight changes in speed. 

In hard-disk systems the motor is 
turned on continuously. This is not 
the case with floppy drives. In fact, 
most drive manufacturers specify 
that the motor should be turned off 
within a second or two after the last 
use of the drive for maximum life of 
both the drive and the diskette. 

Though this is obviously a good 
idea, in practice it slows down opera- 
tion, since there is always a delay of 
about one second from the time the 
motor is turned back on to the time 
the disk can safely be used. Since 
turning the motor on and off is done 
by the disk controller, many micro- 



computer manufacturers leave the 
motor on for 15 to 30 seconds after 
each use; some manufacturers leave 
the motor on continuously. 

Data is written on the disk or read 
back by a read-write head which 
touches the diskette. (Here is another 
difference between a floppy disk and 
a hard disk— in the hard disk the head 
rides above the disk, and [hopefully] 
never touches.) The head can reach 
the disk through a slotted hole in the 
outer jacket, about a half inch wide 
by about 1-1/8 inches long. 

The head is mounted so it can slide 
in and out to reach different tracks. A 
track is a circular path around the 
disk; when the head is positioned 
over a track, the turning of the disk 
continuously rotates the same track 
under the head. That is, the track on a 
computer disk is not like the groove 
on a phonograph record since the 
groove keeps moving closer and clos- 
er to the center of the record as it 
turns; the disk track is a circle that 
does not spiral to the center. 

The head itself is mounted on a car- 
riage which slides in and out on two 
or three metal rods. The carriage, in 
turn, is moved in different ways by 
different manufacturers. The cheap- 
est and most popular arrangement is 
to attach the carriage to a stepper mo- 
tor through either a cam or metal 

Peter A. Stark (PO Box 209, Mt. Kisco, NY 10549 J 
writes extensively on 68xx systems for Microcom- 
puting. 



36 Microcomputing, August 1981 



band so that the rotary motion of the 
motor shaft is translated into a 
straight-line motion of the head car- 
riage. 

The shaft of a stepper motor moves 
in steps in response to an electrical 
signal. This is quite different from the 
normal kinds of motors we are famil- 
iar with, whose shafts turn smoothly 
and continuously; the stepper motor 
turns in discrete steps or jerks. The 
amount of movement per electrical 
pulse depends on the mechanical mo- 
tion of the motor and can be fairly 
well controlled. In general, the me- 
chanical linkage between motor and 
head carriage is such that anywhere 
from one to four motor pulses are re- 
quired to move the head exactly one 
track. 

There is usually a microswitch 
mounted within the drive which 
closes a contact when the head is on 
track zero. The disk controller thus 
keeps track of where the head is by 
first moving the head all the way out 
until the track zero switch closes, and 
then keeping a count of pulses as the 
head is moved into inside tracks. If 
something else should move the head 
in the meantime, then the disk con- 
troller would think the head was on a 
different track from the one it is actu- 
ally at. This is an important concept, 
and will show up again later. 

Another way of moving the head 
carriage is by a voice coil actuator. 
This is a technique used more in stan- 
dard eight-inch floppy drives as well 
as hard disks. Rather than move the 
carriage in discrete steps, the voice 
coil actuator is an electromagnet 
which can move the head in or out in 
one continuous motion. By use of a 
feedback loop and a servo system, 
this system controls carriage speed 
based on how far it has to move. If 
the carriage must move a large num- 
ber of tracks, the voice coil system 
starts it moving very fast and gradual- 
ly slows it down as it gets closer. The 
result is a very fast carriage move- 
ment. 

Even in the stepper systems there is 
a large difference between drives. 
Table 1 shows some typical specifica- 
tions for four important quantities: 
the disk motor startup time (the delay 
from the time the motor is started to 
the time when reading or writing can 
begin), the track-to-track movement 
time (for one track), the carriage set- 
tling time (the delay time after car- 
riage motion stops to the time when it 
stops vibrating enough so it can be 
used) and the head load time (the de- 



lay from the time the head is com- 
manded to touch the disk to the time 
it stops bouncing up and down so it 
can be used). (See Table 1.) 

In what is called single density, one 
track can hold about 2500 bytes, or 
about 20,000 bits. This amount of 
data is not, however, written or read 
all at once. Instead, the track is divid- 
ed into from eight to 18 smaller seg- 
ments called sectors, with each sector 
typically holding either 128 or 256 
bytes, plus a few additional bytes 
which may be used for synchroniza- 
tion or identification of sector. 

To be interchangeable between 
drives, the disk format must be stan- 
dardized and sectors placed in a spe- 
cific place on each track. For that rea- 
son, the disk drive must have a way 
of sensing how far the disk has turned 
from some specific reference point. 

Near the large center hole of the 
diskette are one or more small holes 
which allow the drive and controller 
to sense disk rotation. These holes are 
called index holes; the drive has a 
small light-emitting diode and photo- 
transistor which shines a light 
through this hole and produces a 
pulse output each time the disk turns 
to a position where light can shine 
through the index hole. 

Every type of diskette has one such 
hole which marks the beginning of 
what is called sector 0. In a way, this 
is the beginning of a track, except, of 
course, for the fact that the track is 
continuous and does not really have a 
physical beginning or end. Using this 
as a starting point, the disk controller 
can count sectors to identify all the 
other sectors on the track. 

This is, however, where there is a 
difference between so-called soft-sec- 
tored disks and hard-sectored disks. 
In a soft-sectored disk, there is only 
one index hole, at the beginning of 
sector 0. Before it can be used, such a 
disk must usually first be formatted. 

When formatting, the controller 
steps the head to each new track, 
waits for the sector-0 hole to pass 
through the index sensor light beam, 
and then writes a series of blank sec- 
tors on the track. Each sector is pre- 



ceded by a header which consists of a 
string of synchronization characters 
followed by a sector number. Since 
the rotation speed of the disk is very 
closely controlled, the controller and 
its program have no trouble placing 
each sector in its approximately cor- 
rect spot on the track. 

Since the entire process is software- 
controlled, there does not have to be 
any specific number of sectors per 
track, although from eight to 18 are 
generally used. Typical formats 
might be ten sectors of 256 bytes 
each, or 18 sectors of 128 bytes each. 

Once a soft-sectored disk is format- 
ted, many disk systems no longer use 
the index hole, except perhaps to 
sense whether a disk is inserted in the 
drive or not. Since each sector is 
numbered, it is only necessary to step 
the head to the specified track and 
read off the sector numbers as they 
go past the head until the correct sec- 
tor arrives. 

Hard-sectoring is quite different. 
Now, in addition to the one index 
hole which identifies the beginning 
of a track, there are either ten or 16 
additional holes, evenly spaced 
around the disk, which identify the 
beginning of each sector. (The spac- 
ing between the holes is uneven, so 
the controller can recognize which of 
the holes is the one marking the be- 
ginning of the track.) 

Note that there is no difference in 
drives— the same drive may be used 
for either soft- or hard-sectored disks. 
Only the disk controller and the disk- 
ettes themselves change. 

Soft-sectoring has the advantage of 
being more flexible, since the size of 
the sectors can be varied to meet the 
need. Hard-sectoring, on the other 
hand, can be more efficient since sec- 
tor timing is a bit less haphazard. It is 
also not necessary to number each 
sector, since the controller can use 
the index holes to find each sector on 
the track. 

Soft-sectoring in mini-floppies is 
generally handled by a disk control- 
ler such as the 1771 or 1791. Hard- 
sectoring, on the other hand, is gener- 
ally handled either with discrete cir- 



Time Spec. 


Shugart SA-400 


Wango/Siemens 


82 


MPI 51/52 


motor startup 


1 sec 






1 sec 




1 sec 


track-to-track 


40 ms 






30 ms 




5 ms 


carriage settling 


10 ms 






20 ms 




15 ms 


head load settling 


75 ms 






60 ms 




35 ms 






Table 1. 









Microcomputing, August 1981 37 



Big sale 
onK'sl 

16K...S 149.95 
32K... $199.95 
48K... $249.95 
64K . . . $299.95 




New JAWS-IB 

The Ultrabyte Memory Board 

Due to the tremendous success of our JAWS I, we 
were able to make a special purchase of first-quality 
components at below-cost prices for JAWS-IB. And 
we are sharing our cost saving with you. But don't be 
surprised if the next time you see this ad the prices 
have gone up substantially. Better yet, order now, 
and get the best memory on the market at the best 
price on the market. 

ONE CHIP DOES IT ALL 

laws-IB is the Rolls-Royce of all the S100 dynamic 
boards. Its heart is Inters single chip 64K dynamic 
RAM controller. Eliminates high-current logic parts 
. . delay lines . . . massive heat sinks . . . unreliable 
trick circuits. JAWS-IB solves all these problems. 

LOOK WHAT JAWS-IB OFFERS YOU 
Hidden refresh . . . fast performance . . . low power 
consumption . . . latched data outputs . . . 200 NS 
4116 RAM's . . . onboard crystal . . . RAM Jumper 
selectable on 8K boundaries . . . fully socketed . . . 
solder mask on both sides of board . . . phantom line 
. . . designed for 8080, 8085, and Z80 bus signals . . . 
works in Explorer, Sol, Horizon, as well as all other 
well-designed S100 computers. 



► 



1 0-DAY MONEY-BACK TRIAL: Try a fully wired 
and tested board for 10 days — then either keep 
it , return II for kit, or simply return II In working 
condition. 



? 



Continental U.S.A. Credit Card Buyers Outside Connecticut: 

TO ORDER CALL TOLL FREE 800-243-7428 

From Connecticut Or For Assistance: 

(203) 354-9375 ^B8 

Please send the items checked below: 

JAWS-IB kit: 

D 18K $149.95* 

□ 32K $199.95* 

□ 48K $249.95* 

□ 64K $299.95* 

JAWS-IB Fully Assembled, Wired & Tested: 

D 16K $179.95* 

D 32K $239.95* 

□ 48K $299.95* 

D 64K $359.95* 

Q EXPANSION KIT, 16K RAM Module, to expand 

JAWS-IB in 16K blocks up to 64K. $59.95 
'All prion plus $2 postuee and insurance ($4.00 Canada,). 
Connecticut residents add salt** tax. 

Total enclosed: S 

O Personal Check □ Money Order or Cashier's Check 

D VISA D Master Card (Bank No. ) 



Acct. No. 

Signature 
Print 
Name 



Exp. Date 



Address 

City 

State 



Zip 



l^tNETRONICS R&D Ltd. 

■Ml 333 Litchfield Road, New Milford, IT 06776 



cuitry, or by using some circuitry 
plus a serial synchronous IC such as 
the S2350 USART. 

There is one more sensor in most 
disk drives— the one which tests 
whether a diskette is write-protected. 
Five-inch diskettes have a small 
notch cut into the side, which is de- 
tected either by a microswitch or via 
another photoelectric sensor. If this 
notch is absent, or if it is covered by 
tape, the disk is write-protected and 
the drive will not write on it. 

Compatibility 

The oldest five-inch floppy drives 
were made by Shugart Associates. 
Floppies were originally intended as 
a program transfer medium for mini- 
computers, not as main storage in mi- 
crocomputers. As a result, no one 
ever anticipated that the demand 
would be as large as it has become. 

Shugart soon found itself unable to 
deliver all the drives that customers 
wanted, and hence other companies 
went to work and designed their own 
drives. Although each company 
made its drives slightly differently 
(for patent as well as other reasons), 
the external appearance as well as in- 
terfacing and mounting details were 
generally identical with the Shugart 
drives. Customers could thus switch 
to a different drive without having to 
redesign their products. 

There are some exceptions to this 
(as in Micropolis drives, which have 
traditionally been designed different- 
ly), but in general it is quite possible 
to unplug a Shugart SA-400 drive 
from a system and simply replace it 
by a Wangco/Siemens model 82, a 
Pertec FD-200 or an MPI model 51. 
The drives are the same size, the 



Pin 


Function 


2,4,6 


Spare 


8 


Sector sensor 


10 


Drive select 1 


12 


Drive select 2 


14 


Drive select 3 


16 


Motor on 


18 


In/out step select 


20 


Step pulse 


22 


Write data 


24 


Write enable 


26 


Track sensor 


28 


Write protect sensor 


30 


Read data 


32 


Spare 


34 


Spare 




Table 2. 



mounting screw holes are in the same 
place, and even the power and data 
connectors are the same. 

There is also compatibility in the 
mechanical disk format. Not only do 
all these drives use the same disk, but 
they position their tracks in the same 
place on the disk, and maintain the 
same spacing between tracks. Thus, a 
disk written on one drive can— as- 
suming the drives are properly ad- 
justed—be read on another. 

The tracks are normally spaced 
l/48th of an inch apart; thus they are 
spaced at 48 tracks per inch (tpi). But 
the original Shugart disks had only 35 
tracks, so that the distance between 
the outermost track and the inner- 
most track is only about 3/4 of an 
inch. Since the oval slot through 
which the head reaches the disk is 
about 1-1/4 inches long, there is some 
extra room through which more 
tracks can be placed on the disk. 
Thus, most other disk drive manufac- 
turers allow the head to go in for five 
more tracks, giving a total of 40 tracks. 

(It appears, however, that BASF 
Flexy Disks, and perhaps others, 
have a shorter slot and cannot be 
used for 40 tracks.) 

Though 40-track drives provide 
five more tracks than 35-track drives, 
the spacing between tracks and the 
positions of the first 35 tracks are 
identical. Thus, a 40-track drive can 
be used in a 35-track system and still 
be completely interchangeable. 

Electrical Interface 

Almost all five-inch floppy disk 
drives are advertised as being elec- 
trically Shugart-compatible. Since the 
same kind of connector is used in all, 
and since the logic signals almost al- 
ways use the same pins in the connec- 
tors, there is true compatibility be- 
tween them. (Except in one respect— 
an operating system designed to 
work with a drive which has fast 
head load time or fast carriage move- 
ment will not provide enough time 
for a slower drive.) 

A five-inch drive connects to the 
system via two connectors and a sin- 
gle push-on-type ground lead. 

A four-pin connector is used to 
bring power to the drive. A typical 
drive requires + 5 V at about 0.5 amp, 
and + 12 V at about 1 amp while run- 
ning, and perhaps up to 1.8 amp 
when the motor is just starting. 

The power connector needed is an 
AMP part number 1-480424-0 with 
four AMP 61473-1 or 60619-1 pins. It 
is most easily obtained as cat. no. 2480 



Microcomputing, August 1981 



from Hobby World (HW) Electronics 
for $1.99 each. 

The data connection between the 
drive and its controller is normally 
done via a 34-wire flat cable with a 
34-pin card-edge connector on the 
drive end of the cable. Suitable con- 
nectors are AMP part number 
583717-5 or 3M Scotchflex 3463-001. 
These connectors crimp into the 
34-conductor cable. 

The other end of the cable usually 
attaches to its connector via another 
34-pin card-edge connector, although 
sometimes a plug/socket connector is 
used, usually a 3M Scotchflex 3414- 
0000 or 3414-6000. (The matching 
connector for the controller board is 
then a 3M Scotchflex 3431-1002 right- 
angle connector or 3431-2002 straight 
connector.) 

The 3M Electronic Products Divi- 
sion has sales offices in many U.S. 
cities, but the connectors are diffi- 
cult to get because of minimum or- 
der requirements at their distribu- 
tors; thus most computer users buy 
ready-made cables. 

I have found two sources of these 
connectors, and the 34-wire cable, 
which are quite convenient: 
Electrolabs (PO Box 6721, Stan- 



ford, CA 94305, 800-227-8266) has 
the wire at 68 cents per foot, card- 
edge connectors at $6.64, pin-type 
plugs at $6.58 and sockets at $4.47; 
the right angle pin-type plug for a 
controller board costs $2.77. 

Another source is the International 
Minicomputer Accessories Corp. (In- 
mac), which has offices in most large 
U.S. cities, including Los Angeles, 
Denver, Dallas, Chicago, Detroit, 
Washington, DC and Boston. Their 
current prices are as follows: no. 
1603 cable is $1.20 per foot, no. 1627 
card-edge connector is $7.20, no. 
1653 pin-type socket connector is 
$6.95 and the no. 1633 pin-type con- 
nector to a controller board is $4.70. 

(These connectors are similar to 
those used on eight-inch drives, ex- 
cept that eight-inch drives use 
50-conductor cable and connectors.) 

A special— and expensive— crimp- 
ing tool is recommended for crimp- 
ing the cable connectors onto the flat 
ribbon cable. A very large bench 
vise could also be used (small, port- 
able vises will not do the job), but I 
have had luck with a drill-press vise. 
In any case, very careful assembly is 
required because the connector can- 
not be removed from the cable once 



installed without damaging it. 

Within the 34-conductor cable, the 
wires are numbered from 1 through 
34, and all odd-numbered wires are 
used as ground. In other words, 
there is a ground wire separating 
each pair of adjacent data or control 
wires. On a card-edge or pin-type 
connector, however, all the odd- 
numbered pins appear on one side of 
the connector, while the even- 
numbered pins are on the other side. 
When the card-edge connector is 
plugged onto the edge of the board, 
all the grounds are on one side of the 
board, while the signal and control 
leads are on the other side. 

Since card-edge connectors are sel- 
dom keyed, it is easy to plug the con- 
nector on the board backward, there- 
by shorting all the drive signal leads 
to the controller's ground and vice 
versa. This generally causes no dam- 
age (and is signalled by the fact that 
the drive motors run and don't stop), 
but should definitely be avoided. 

Connector assignments are shown 
in Table 2. 

(Note that some manufacturers re- 
fer to the first drive as drive 0, while 
others call it drive 1.) 

All of these signals are normally 




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Microcomputing, August 1981 39 



high (above + 2.4 V) and go low (near 
ground) when on. For example, to se- 
lect drive 1, the controller would 
bring line 10 low, while keeping the 
other drive select lines high. 

In multidrive systems, all drives 
are connected in parallel across the 
same 34- wire cable; the customary 
method is to crimp several card-edge 
connectors on the cable, separated by 
six to ten inches, with each connector 
plugged into a drive. All the signals 
are shared except for the drive se- 
lects. (This explains why all motors 
go on and off together in multidrive 
systems— there is only one motor 
control line.) 

There is a difference here between 
five-inch and eight-inch drives. Five- 
inch drives use dc motors, and con- 
tain circuitry to turn the motor on 
and off in response to the motor con- 
trol signal on pin 16. Eight-inch 
drives use ac motors which run di- 
rectly off the 115-V (or 230- V) power 
line, and do not have any power con- 
trol circuit. The motors will either 
stay on continuously or else require 
another circuit board for motor con- 
trol. 

The line assignments shown in Ta- 
ble 2 only provide for three drives, 
whereas in many systems four drives 
are desired. Line 6 or 32 is often used 
as a fourth drive select line. Drives 
which provide a door-lock mecha- 
nism to prevent the door from being 
opened while the drive is being used 
may use line 4 for that purpose. 

When all drives are off, all drive se- 
lect lines are held high by the control- 
ler. To select a particular drive, the 
controller pulls its drive select line 
low. That enables that drive to re- 
spond to the other control lines, 
while all remaining drives on the sys- 
tem remain disabled (or deselected). 
Fig. 1 shows the wiring of a shunt, 
which is found inside each drive. The 
shunt has a small DIP-IC-like body 
which is plugged into an IC socket 
right near the card-edge input con- 
nector. The shunt is essentially a se- 
ries of jumpers which connect oppo- 
site pins on the IC socket together un- 
less broken; there is a thin area in the 
center of each jumper intended to be 
broken. (I've found that an easier— 
and reversible— method is to unplug 
the shunt from its socket, and simply 
bend up the pins to be disconnected 
before plugging it back in.) 

The Dl, D2 and D3 shunts select 
whether this drive will be the first, 
second or third drive in a system 
(TRS-80 owners— read on, because 



the TRS-80 does it slightly different- 
ly). For example, if the Dl shunt is 
left connected while D2 and D3 are 
broken, then this will be the first 
drive. Whenever drive select 1 goes 
low, the main drive select line inside 
the drive will therefore go low, and 
the drive will be selected. If D2 and 
D3 are broken, then nothing will hap- 
pen here when the other drives are 
selected. 

The HS and HM jumpers work to- 
gether; one of them must always be 
installed while the other must be 
broken. These shunts control the 
head load solenoid. This is the sole- 
noid which brings the disk up against 
the read/write head when reading or 
writing is about to be done. If the HS 
shunt is in place, then the head will 
load only when the drive is selected; 
if the HM shunt is in place the head 
will load as soon as the motor goes 
on. Either jumper could be used in a 
single-drive system. The HS shunt is 
usually used in multidrive systems 
because it results in less disk wear, 
and also in less likelihood of an acci- 
dental disk erasure in case of a hard- 
ware problem. 

Systems using double head drives, 
however, often use the HM jumper 
even in multidrive systems. Although 
this increases the disk wear since the 
head is in continuous contact with 
the disk as long as the motor is turn- 
ing, it reduces the severe disk wear 
which occurs when the two disk 
heads suddenly come together and 
clamp the disk between them. With 
the HM option, the heads only load as 
the motor goes on, not each time the 







HS 

Dl 

D2 

03 

MX 

HM 


= 







(a) SHUNT APPt 


'ARA 


NCi 


r 






1 




TO HEAD LOAD 




HS 

e - -o — 




SOLENOID 


DRIVE 


SELECT 1 


01 

o- - -©— < 

02 


t 




— * DRIVE SELECT 


DRIVE 


SELECT 2 


o --o— i 








DRIVE 


SELECT 3 


03 
o --o— 










MOTOR ON 


HM 














TO MOTOR 










m CONTROL 








CKT 






(b) DIAGRAM 








Fig. 1. 


Thes 


hun 


t. 





drive is selected. 

The MX jumper leaves the drive al- 
ways selected when in place. This 
would normally be used only in sin- 
gle-drive systems. 

In most multidrive systems the 
drives are connected in parallel 
across the 34-pin cable, and each 
drive gets all three drive-select sig- 
nals; the selection of drives is then 
done by breaking two out of the three 
jumpers in the shunt. This means, of 
course, that you have to open the 
drive cabinet and manipulate the 
shunt. 

Right next to the shunt, in an adja- 
cent IC socket, is a resistor network 
that contains pull-up resistors which 
act as loads on the signal lines coming 
from the controller. New drives al- 
ways come with this resistor package 
installed, but in multidrive systems 
only one resistor pack should be 
used, in the drive which is connected 
farthest from the controller. Again, 
this means that you must open the 
drive cabinet and remove all but one 
of these packs when installing a sys- 
tem. 

In the case of the TRS-80, Radio 
Shack apparently did not want cus- 
tomers poking around the inside of 
the disk cabinets, and so they made 
three changes. First, they added a 
short extender board to the drive to 
bring the 34-pin card-edge connector 
outside of the cabinet (normally it is 
inside). Second, they gave the first 
disk drive a different part number 
from add-on drives, and they always 
supply the first drive with the resistor 
pack in place, while the add-ons have 
it already removed. This is the only 
difference between the two types of 
drive, but it does eliminate the need 
to open the box at all. 

Finally, they left all three drive-se- 
lect jumpers in place on each drive 
(with Dl, D2, and D3 all connected), 
and instead do the drive selection in 
the cable by physically yanking out 
the appropriate pins from the card- 
edge connector. For example, the 
connector for the first drive has pin 
10 but no pin 12, 14 or 32. Thus, the 
drive-select 2 and 3 signals do not 
even get to the drive, and so the fact 
that all three drive-select jumpers in 
the shunt are still there makes no dif- 
ference. 

Since the TRS-80 can support up to 
four drives, pin 32 is generally used 
as the fourth drive select. Some 
drives have pin 32 wired for that use, 
while in others pin 32 is a spare, or is 
even used for another purpose. For 



40 Microcomputing, August 1981 



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example, MPI model 51 drives use 
pin 32 to activate a side-select circuit 
(which is on the drive's printed cir- 
cuit board, but not used). Thus, MPI 
51 drives supplied for use with the 
TRS-80 usually have the trace to pin 
32 cut, and a small wire jumper add- 
ed to connect pin 32 to pin 14 or some 
other point in the drive-select circuit. 
This is something which must be 
kept in mind if you switch either 
drives or cable between the TRS-80 
and other computers. 

Recording Method 

To compensate for slightly differ- 
ent rotating speeds of the diskette, 
the signal written on the disk con- 
tains both data and clock pulses. Al- 
though the actual signal written on 
the disk is somewhat different, the 
read or write signal as it travels be- 
tween the disk drive and its control- 
ler looks like that in Fig. 2. 

Clock pulses spaced eight micro- 
seconds (/is) apart are recorded con- 
tinuously on the disk, with data pulses 
placed roughly halfway between 
clock pulses. When a 1 is being writ- 
ten, the controller inserts a data pulse 
between the clocks; for a the con- 
troller omits the data pulse. 

If the data is a long string of zeroes, 
then only the clock pulses will exist 
with a spacing of eight us. In a long 
string of ones, on the other hand, 
pulses appear every four us. This is 
the reason why this method is called 
FM encoding, since the frequency of 
the pulses (which is one divided by 
the spacing) is low for a zero, high for 
a one. (Except for the timing, this 
scheme is very similar to that used in 
a TRS-80 cassette recording. In a Lev- 
el II TRS-80 system, the spacing be- 
tween cassette clock pulses is 2000 
us.) 

Thus, disk data bits are spaced 
eight us apart for a total of 125K bits 
per second. A complete eight-bit 
byte, therefore, is written or read 
every 64 us. 

Disk data is written serially, one bit 
at a time. Since a microprocessor is 
simply not fast enough to convert 



CLOCK 



CLOCK 



CLOCK 



CLOCK 



DATA*0 



DATA = I 



DATA = 



Fig. 2. FM data encoding. 



data to or from serial format at eight 
us per bit, the conversion is always 
handled by external circuitry such as 
a 1771 disk controller or a USART. 

This controller or USART, how- 
ever, handles complete characters at 
a rate of one every 64 us. Most micro- 
processors are fast enough that they 
can move characters between the 
controller and main memory under 
program control as long as the pro- 
gram coding is carefully done and 
properly timed. 

The data encoding described so far 
is the original recording and timing 
method, and is called normal or sin- 
gle density. 

Double Density 

In looking at Fig. 2 we see that 
every bit in single-density recording 
is accompanied by its own clock 
pulse. Hence the presence of the 
clock pulses effectively doubles the 
bit density of the disk— if we record 
125,000 ones on the disk in one sec- 
ond, we are actually writing 250,000 
pulses. Hence the disk drive as well 
as the diskette must be capable of 
handling pulses at a 250K bit per sec- 
ond rate. 

If the clock pulses could be elimi- 
nated, then all of these 250K pulses 
could be used for data. This would 
double the data transfer rate, and 
would also double the storage capaci- 
ty per disk. 

This is the idea behind double den- 
sity. Through a slightly revised en- 
coding scheme called MFM (modi- 
fied FM) or M2FM, the data and 
clock bits are combined, and there- 
fore twice as much data can be 
stored. Since the effective data rate as 
far as the drive and diskette are con- 
cerned is unchanged, the same drive 
and disk can be used for double den- 
sity as well as single— except for 
some very early disk drives (which 
are marginal performers), all floppy 
disk drives can be used with double 
density. 

Note, though, that although double 
density doesn't affect the disk or 
drive, it does affect the computer. At 
double-density recording, the data 
bits are now only four us apart, and 
thus a complete byte is transmitted in 
32 us instead of 64. At 64 us each 
character could be processed by the 
microprocessor; at 32 us there is 
much less time. Some processors, 
such as the 6809, are fast enough that 
with some very careful program cod- 
ing, data can be moved to and from 
memory at that rate; but most com- 



42 Microcomputing, August 1981 



mon processors are not. 

Thus, with some double-density 
disks, data must go to and from mem- 
ory without going through the pro- 
cessor; that is, the controller must be 
able to bypass the processor and ac- 
cess memory itself. Thus, a double- 
density controller is more expensive 
and more complex than a single-den- 
sity one. 

One technique for doing this is via 
DMA, or direct memory access. 
When DMA is being used, the main 
processor starts the controller and 
then disconnects itself from the com- 
puter buses. The controller takes 
over and controls the address and 
data buses, as well as read/write and 
other control lines, and does its own 
transferring of data. 

In most systems, a data byte can be 
transferred to or from memory in un- 
der one us. Since data bytes are only 
transferred once every 32 us, there is 
plenty of time to do a DMA transfer. 
In a simple system, the microproces- 
sor might relinquish the buses long 
enough to transfer an entire sector's 
worth of data to or from the control- 
ler, but this obviously wastes time. In 
more complex systems the controller 
generates interrupts when it needs 
the bus, and the processor releases 
the bus just long enough to transfer 
one byte. 

Either way, though, system timing 
becomes very complex. If there are 
sources of other interrupts or if the 
computer is being used for time-criti- 
cal work, then the overall operation of 
the DMA circuitry must be watched 
very carefully. 

Thus, some of the most expensive 
double-density controllers use a dif- 
ferent technique. Instead of using 
DMA access to the main memory, 
these controllers have their own 
memory on the controller board, just 
big enough to store data from one sec- 
tor. When reading or writing on the 
disk, the controller transfers data be- 
tween its own memory and the disk 
at high speed. But data transfer be- 
tween the main computer memory 
and the controller's memory can be 
done by the processor itself, under 
program control, when convenient. 
Though this scheme appears to be 
slower because it involves double 
data transfer, in practice it avoids 
other difficulties, and so is just as 
good as direct DMA but much sim- 
pler. 

(This may be a good place to com- 
pare standard eight-inch floppy re- 
cording with the five-inch floppy. In 



the eight-inch floppy, the diskette ro- 
tates faster; the data bits also appear 
more often because the track diame- 
ter is larger, and thus there are more 
bits per track. As a result, the timing 
in single-density recording is half of 
that shown in Fig. 2— the clock bits 
are 4 us apart instead of eight. Thus, 
single-density must handle a byte 
every 32 us, while double-density re- 
cording handles a byte every 16 us. 
Thus eight-inch floppy controllers al- 
most always use DMA or internal 
memory buffering on micro systems. 
This explains why five-inch control- 
lers are so much cheaper. For exam- 
ple, a five-inch controller for a 6800 
system can be purchased for under 
$100, whereas an eight-inch control- 
ler costs several times as much.) 

So we see that double-density re- 
cording doubles the number of bits 
per disk as well as doubles the data 
transfer rate. 

Double-Sided Operation 

Floppy diskettes are coated with 
oxide on both sides even though they 
are intended for single-sided opera- 
tion. This is probably done for me- 
chanical reasons— so the diskette 
doesn't warp— but it does mean that 
the back side of the floppy can also be 
used. 

When the read/write head in a 
drive is touching the diskette, a pres- 
sure pad on the opposite side presses 
the diskette against the head. To al- 
low the pressure pad access to the 
diskette, the diskette jacket has a slot 
on both sides. This again means that 
the disk can be used on both sides. 
(Note, however, that diskette manu- 
facturers do not test the back side of 
diskettes, and so the back side may 
sometimes produce errors. Special 
double-sided diskettes are available 
at extra cost and are tested on both 
sides.) 

There is still a problem, however. 
The index sensor hole is not located 
in a symmetrical location. That is, 
when the diskette is turned over in 
the drive, the sensor hole is in a dif- 
ferent place. Thus, in a basic drive, it 
cannot be read. 

Some disk drive manufacturers 
have solved that problem by install- 
ing two parallel index sensors, one 
for use when the disk is inserted cor- 
rectly and the other when the disk is 
inserted backward. With these drives, 
sometimes called flippy drives, it is 
easy to write on either side of a disk. 
(A second write-protect sensor is also 
required, since the write-protect 



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notch is also in a different place now.) 
But even if dual sensors are not in- 
cluded, it is fairly simple to punch an 
extra set of holes in the diskette jack- 
et— carefully!— to allow the single in- 
dex sensor to check the index holes. 
Several suppliers are selling flippy 
kits for doing this; I have been doing 
it for years with a hand paper punch 
from a local stationery store. 

Diskette manufacturers warn 
against the practice, however. As a 
diskette is used, the fiber layer inside 
collects dirt and dust and holds onto 
it. If the diskette is turned around, it 
now turns in the opposite direction, 
and hence much of this dirt and dust 
is released. They warn that this could 
result in increased disk and head 
wear as well as data errors. 

The entire problem is alleviated 
with the new drives that provide two 
read/write heads, one on each side of 
the disk. Now either side of the disk 
can be written without turning the 
disk over. Not only does this double 
the storage per disk, but all the data 
on the disk is immediately usable. In 
other words, rather than appearing as 
two different disks, the disk can now 
be formatted as a single, large disk of 
double the capacity. 

The idea of double-sided drives is 
fairly old, but until recently the drive 
manufacturers had trouble with the 
mechanical design. When the disk 
was clamped between two heads, it 
was often damaged by excessive 
pressure. In early designs, both heads 
were moved to and from the disk by 
the head load solenoid; most current 
designs leave one head in place and 
just move the other. 

As far as the electrical interface is 
concerned, all of the leads on the 
34-pin data connector remain the 
same except for one. Pin 32, which 
was formerly a spare, is now used to 







HS 
DSI 


• 




tf 


DS2 


W 


DS3 


^ 


\ 


MX 


» 


i 


HM • 


i 
J 


i 



WIRE JUMPER TO PIN 32 
(SIDE SELECT) OF 34 
PIN CONNECTOR 



Fig. 3. Hardware side-select circuit. Diodes must 
be germanium junction diodes, not silicon. 



select the side. When this pin is high, 
the drive uses the normal side of the 
disk; if pin 32 is low, it uses the re- 
verse side. With this convention, if a 
double-sided drive is plugged into a 
single-sided controller, pin 32 will be 
unconnected and therefore allowed 
to go high. The drive will then use the 
normal side as if it was single-sided. 
It's important, though, to watch out 
for drives which are wired to use pin 
32 for a fourth drive select. If these 
are mixed with double head drives in 
one system, some modifications will 
be needed. 

Double-Track Drives 

In normal five-inch drives, track 
spacing is held at 48 tracks per inch, 
and the total number of tracks is 
either 35 or 40. (Compare this with 77 
tracks on an eight-inch drive.) 

Several manufacturers, however, 
make drives which use narrower 
tracks and place them closer to- 
gether. For example, the MPI model 
91 and 92 drives use spacing of 96 
tracks per inch, and so have room for 
80 tracks instead of 40. (The model 92 
is double-sided, and so has a total of 
160 tracks, 80 on each side.) 

In these drives, track is in the 
same place as track on a normal 
drive; track 2 is located the same as 
track 1 in a normal drive, and so on. 
Hence the even-numbered tracks lie 
on top of normal, or single-track, 
track positions; the odd tracks are 
sandwiched between. Thus, a dou- 
ble-track drive can read a normal 
diskette assuming that the software is 
written to do double-track stepping. 
(But it cannot write in normal track 
spacing because its tracks are nar- 
rower and it does not fully erase pre- 
vious data over the entire wide track 
width on previously used disks.) 

Double-track drives are substan- 
tially more expensive than single- 
track drives because of much closer 
mechanical tolerances required. 
Since the tracks are narrower, it be- 
comes much more important to 
maintain disk-to-drive alignment. 
This means that the disk must be cen- 
tered on the spindle more accurately, 
and much closer attention must be 
paid to temperature compensation 
and alignment. Some users also have 
some reservations about long-term 
stability. 

The MPI Model 92 Drive 

I recently obtained an MPI Model 
92 drive. This drive is capable of dou- 
ble-density, double-sided operation, 



44 Microcomputing, August 1981 





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Microcomputing, August 1981 45 



and double-track spacing. Thus, it 
can hold eight times as much data on 
line as a standard single-density disk. 
At 160 tracks, with 20 256-byte sec- 
tors per track, this translates to 
819,200 bytes of data per disk. 

In actual use, though, total disk ca- 
pacity is somewhat less than 819K for 
two reasons. First, soft-sectored disk 
systems require that each sector be 
preceded by some sync bytes and 
sector identification; this information 
takes up room and so the number of 
sectors per track is usually slightly 
less than 20; 18 is more common. Sec- 
ond, double-density systems general- 
ly use record track in single-density 
mode. As a result, track of all disks 
can be read on all systems, regardless 
of whether they are single or double 
density. Since track contains infor- 
mation regarding the format of the 
rest of the disk, the disk operating 
system can then set itself to read the 
rest of the disk. Thus, though the the- 
oretical capacity of such a disk is 
819K bytes, in most cases the actual 
storage is somewhat under 800K. 

The ultimate aim is to use it with a 
double-density controller; initially, 
though, I decided to test it at single 



density with two existing controllers 
on my 6800 system. 

The first job was to modify the ex- 
isting operating system to allow the 
use of 80 tracks per side. This is a 
very system-specific job, and I won't 
describe that here. 

The next job was to make use of the 
second side. One way is to add a side- 
select circuit to the controller, and 
modify the disk operating system to 
keep this output high on the first 80 
tracks and low on the second 80 
tracks. A much better way would be 
to keep alternate tracks on opposite 
sides of the disk, since this would 
minimize head carriage movement 
while reading a file. 

Both of these tasks require quite a 
bit of work, as well as a good knowl- 
edge of the (usually undocumented) 
disk operating system. I therefore 
chose a slightly different approach. 

Instead of the plug-in shunt inside 
the drive, I substituted a plug-in DIP 
header. This is an assembly which 
plugs into an IC socket and is usually 
used to allow simple connection of 
discrete components like resistors to 
a digital logic circuit. 

On this header I put the circuit 



shown in Fig. 3. The HS jumper is a 
wire, while the DS2 and DS3 jumpers 
are replaced by two germanium di- 
odes. (Note: these diodes must be ger- 
manium junction diodes, not silicon. 
I used the base-emitter junctions of 
two old germanium transistors.) Fi- 
nally, a short jumper from the DS3 
diode's cathode was soldered to a tab 
connected to pin 32, the side select 
lead, of the 34-pin connector. 

Using this circuit, the drive is se- 
lected as both drive 2 and drive 3, via 
the diodes. When either drive-select 
signal goes low, the diode pulls the 
drive's own select line low. (Germa- 
nium diodes must be used because 
they have the low-voltage drop need- 
ed to pull the output low enough. Sili- 
con diodes don't work in this applica- 
tion.) 

Thus, this one drive looks to the 
system as both drive 2 and drive 3. 
But when selected as drive 2, the 
side-select signal is high and so it uses 
the front side of the disk. When se- 
lected as drive 3, the side-select signal 
is low, and so it uses the back side of 
the disk. 

Both sides of the disk are now us- 



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^180 



46 Microcomputing, August 1981 



able and on-line at the same time, ex- 
cept that they are seen by the system 
as separate drives. Though this does 
give the full capacity of the disk, this 
arrangement has one disadvantage— 
if both sides were seen as just part of 
one disk, a very large file (larger than 
one side) would automatically be 
split so it lies partially on each side. 
However, this scheme does not allow 
that. 

Does It Work? 

This connection was tied with two 
different controllers and operating 
systems, but on the same computer. 
In one case it worked; in the other, it 
did not. 

To avoid wasteful head movement, 
most operating systems keep track of 
the last position of the head carriage 
on each drive. For example, if the 
system writes data on track 13 and 
then goes elsewhere to perform an- 
other operation, when it returns to 
the drive it assumes that the head is 
still on track 13. This is a reasonable 
assumption to make. 

But when a double-sided drive is 
wired as two separate drives, both 
sides must be on the same track. Sup- 



pose that the system moves drive 2 to 
track 13 and then does a read from 
track 30 of drive 3. Not knowing that 
this read has also moved the head on 
drive 2 to track 30, it now returns to 
drive 2 and expects its head to still be 
on track 13. But it's not, so we're in 
trouble. 

One of my disk systems is soft-sec- 
tored and uses a 1771 controller. 
Since every sector on a soft-sectored 
disk is numbered, not just with the 
sector number, but also track num- 
ber, then the 1771 controller immedi- 
ately realizes that it's on the wrong 
track. It tries to re-read the sector a 
few times, but after two seconds or so 
does a seek back to track and then 
back to the desired track. Thus there 
is a slight delay, but eventually it gets 
to the right track and reads or writes 
in the correct sector. The delay slows 
down operation, but is only present 
when alternate sides of the same disk 
are both used; if only one side is used 
continuously, then this problem does 
not appear. 

My other disk system is hard-sec- 
tored. In this system, sectors need not 
be numbered (since the index holes 
are used to find the correct sector). 



Thus, when the operating system 
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no way of knowing that the head has 
been moved from its earlier position. 
And so it reads or writes in the wrong 
place, a serious mistake. 

There are, of course, several ways 
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The best method would be to do both 
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TECMAR,INC 

(216) 464-7410 



23600 Mercantile Road • Cleveland. OH. 44122 



•See List of Advertisers on page 194 



Microcomputing, August 1981 47 



This popular printer sets a high standard for dot matrix print quality. 



The Epson MX-80: 
A Tough Act to Follow 



By Frank J. Derfler 



A home computer has many uses, 
but a lot of them are not really 
practical. For instance, I don't think 
anyone can honestly claim it is more 
convenient to keep recipes in a mi- 
crocomputer than in a file box. But 
one of the most practical things you 
can do with a microcomputer is word 
processing. Most of us can see the 
value of being able to edit and cut and 
paste letters and other documents on 
a video screen before printing. The 
only drawback is the cost of a good 
letter-quality printer. 

Three Approaches 

There are essentially three ways to 
attack the printer problem. A high- 
quality high-speed printer will cost a 
minimum of $2000, and could run 
over $4000— that cost might be pro- 
hibitive. You might also require some 
unique software to fully exploit the 
power of an expensive printer. The 
quality, though, will be something to 
be proud of. 

Surplus Printing Terminals 

A middle-of-the-road approach in- 
volves using surplus printing termi- 
nals. The surplus terminals probably 
started life as input devices at car 
rental, airline or other remote loca- 
tions serving large time-shared com- 
puter systems. These large systems 
usually did not use ASCII as a data al- 
phabet, and they may not have used 
RS-232C as a signalling scheme. 
Many available systems have been 



converted to RS-232C ASCII com- 
munications, but the quality of the 
conversion varies. These surplus 
printing terminals are usually based 
on an IBM Model 72 Selectric type- 
writer, so the print quality can be ex- 
cellent and you can change typeballs. 
On the positive side, surplus print- 
ing terminals offer moderate cost 
($600-$ 1200) and high quality. On 
the negative side, the quality of con- 
versions and mechanical refurbish- 
ing is inconsistent. The speed is 
limited to about 110 baud. The print- 
ing mechanism is a mechanical night- 



mare for the uninitiated, although 
most local typewriter repair shops 
will recognize and repair the IBM 
mechanism once you persuade them 
to take a look at your unique beast. 
The cost of maintenance for the print- 
ing mechanism may be $ 100 a year or 
more. 

Dot Matrix 

Until recently, the last choice of 
anyone doing word processing was a 
dot matrix printer. The only things 
dot matrix systems had going for 
them were price and convenience. 







Frank J. Derfler, Jr. (PO Box 691, Herndon, VA 
22070) is the author of the monthly Dial-up Direc- 
tory column in Microcomputing. 



The Epson printers contain a microprocessor which controls all functions. The empty sockets in the center 
of the picture hold additional ROMs for the GRAFTRAX II graphics option. GRAFTRAX II provides a 
great deal of capability in addition to the TRS-80 graphics set. It gives the MX-80 a high density graphics 
mode and italics in all 12 print modes. The GRAFTRAX II option costs $95 as a dealer installed retrofit 
and $50 if it is installed at the factory. The optional RS-232C serial board and an 1 EEE-4HH standard inter- 
face board are also available. 



48 Microcomputing, August 1981 




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It's a convenient, uncomplicated, 
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CP/M users: specify disk systems and formats Most formats available 



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Medical(PAS-3) $849/$40 

Dental (PAS-3) $849/$40 



ASYST DESIGN 

Prof Time Billing 
General Subroutine 
Application Utilities 



$549/$40 
$269/$30 
$439/$30 



COMPLETE BUS. 

Creator 

Reporter 

Both 



SYSTEMS 

$269/$25 
$169/$20 
$399/545 



MICROSOFT 

Basic-80 

Basic Compiler 

Fortran-80 

Cobol-80 

M-Sort 

Macro-80 

Edit-80 

MuSimp/MuMath 

MuLisp-80 

ORGANIC SOFTWARE 



COMPUTER CONTROL 

Fabs(B-tree) $159/$20 

UltraSortll $159/$25 

COMPUTER PATHWAYS 

Pearl (level 1) $ 99/$25 

Pearl (level 2) $299/$40 

• Pearl (level 3) $549/$50 

DIGITAL RESEARCH 

CP/M 2 2 

NorthStar 

TRS-80 Model II (P + T 

Micropohs 

Cromemco 
PL/l-80 
BT-80 
Mac 
Sid 

• Z-Sid 
s Tex 

DeSpool 



$149/$25 
$159/535 
$l69/$25 
$189/$25 
$459/$35 
$179/$25 
$ 85/$15 
65/$ 15 
90/$ 15 
90/$ 15 
50/$ 10 



DMA. 

Ascom 
DMA-DOS 
CBS 
Formula 

GRAHAM-DORIAN 

General Ledger 
Acct Receivable 
Acct Payable 
Job Costing 
Payroll II 
Inventory II 
Payroll 
Inventory 
Cash Register 
Apartment Mgt 
Surveying 
Medical 
Dental 

MICRO AP 
S-Basic 
Selector IV 



$149/$15 
$179/$35 
$369/$45 
$539/$45 

$729/$40 
$729/$40 
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$493/$40 
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$729/$40 
$729/$40 

$269/$25 
$469/$35 



TextWriter III 
DateBook II 
Milestone 

OSBORNE 

General Ledger 
Acct Rec/Acct Pay 
Payroll w/Cost 
All 3 
All 3 + CBASIC-2 

PEACHTREE" 

General Ledger 
Acct Receivable 
Acct Payable 
Payroll 
Inventory 
Surveyor 
Property Mgt 
CPA Client Write-up 
Mailing Address 

SOFTWARE WORKS 

Adapt (CDOS to CP/M) 
Ratfor 

SOHO GROUP 

MatchMaker 
Worksheet 



$289/$30 
$329/$30 
$349/$30 
$574/$30 
$124/$30 
$144/$20 
$ 84/$20 
$224/$25 
$174/$20 

$111/$20 
$269/$25 
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$ 59/$20 
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$129/$60 
$199/$75 

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$ 69/$na 
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$ 97/$20 
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PASCAL 

Pascal/MT + $429/$30 

Pascal/Z $349/$30 

<s Pascal/UCSD $399/$50 

Pascal/M $149/$20 

WORD PROCESSING 

^WordSearch $179/$ 50 

SpellGuard $229/$25 

VTS/80 $259/$65 

Magic Wand $289/$45 

Spell Binder $349/$45 



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The Last One 

SuperCalc 

Target 

BSTAM 

Tiny C 

Tiny C Compiler 

CBASIC-2 

Nevada Cobol 

MicroStat 

Vedit 

ESQ-1 

MiniModel 

StatPak 

Micro B + 

Raid 

String/80 

Stnng/80 (source) 



APPLE II 



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$269/$ 50 
$189/$30 
$149/$15 
$ 89/$ 50 
$229/$50 
$ 98/$20 
$129/$25 
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$229/$20 
$224/$35 
$ 84/$20 
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MICRO DATA BASE SYSTEMS 

HDBS $269/$35 

MDBS $795/$40 

DRSorQRSorRTL $269/$35 

MDBS PKG $1295/$60 

MICROPRO 

WordStar $319/$60 

Customization Notes $ 89/$na 
Mail-Merge $109/$25 

WordStar/ Mail-Merge $419/$85 
DataStar $249/$60 

WordMaster $119/$40 

SuperSort I $199/$40 



STRUCTURED SYSTEMS 

GLor ARor APorPay $599/$40 

Inventory Control $599/$40 

Magic Worksheet $219/$40 

Analyst $199/$25 

Lettenght $179/$25 

QSort $ 89/$20 

SUPERSOFT 

Diagnostic I $ 49/$20 

Diagnostic II $ 84/$20 

Disk Doctor $ 84/$20 

Forth (8080 or Z80) $149/$25 

Fortran $219/$30 

Fortran w/Ratfor $289/$35 

Other less 10% 

TCS 

GLor ARor APorPay $ 79/$25 

All 4 $269/$99 

UNICORN 

Mince $ 99/$25 

Scribble $ 99/$25 

Both $189/$50 

Amethyst $299/$75 

WHITESMITHS 

C Compiler $600/$30 

Pascal (mcl C") $850/$45 

DATA BASE 

FMS-80 $649/$45 

dBASE II $629/$50 

Condor $599/$30 

Condor II $899/$50 

Access/80 $749/$50 



INFO UNLIMITED 

EasyWnter $224 

Datadex $349 

Other less 15% 

MICROSOFT 

Softcard(Z-80CP/M) $259 

Fortran $179 

Cobol $499 

MICROPRO 

Wordstar $269 

MailMerge $ 99 
Wordstar/MailMerge $349 

SuperSort I $159 

PERSONAL SOFTWARE 

Visicalc $ 99 

Visicalc II $159 

CCA Data Mgr $ 84 

Desktop/Plan II $159 

Visiterm $129 

Visidex $159 

Visiplot $149 

Visitrend/Visiplot $229 

Zork $ 34 

PEACHTREE" 

General Ledger $224/$40 

Acct Receivable $224/$40 

Acct Payable $224/$40 

Payroll $224/$40 

Inventory $224/$40 

OTHER GOODIES 

dBASE II $329/$50 
VU #3(usew/Visicalc) $ 49 

Super-Text II $127 

Data Factory $129 

DB Master $184 
OEM (complete 

acctmg) $399 

Charles Mann less 15% 

STC less 1 5% 



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The appearance of the dot matrix 
characters was definitely a negative 
factor. It took a large lump of ratio- 
nalization and some self-deception to 
convince yourself that people en- 
joyed reading letters prepared on a 
standard dot matrix printer— they 
didn't, and they still don't. 

But several new dot matrix ma- 
chines that provide good to superb 
print quality have recently hit the 
market. As usual, there are some 
trade-offs in cost vs quality. The best 
dot matrix machines cost as much as 
the daisywheel and thimble ma- 
chines, but provide more flexibility 
in operation. However, the most pop- 
ular machine has a low price, and a 
print quality suitable for personal let- 
ters and documents for other com- 
puter users. This kind of printer is ex- 
emplified by the Epson MX-80. 

10 r 000 a Month 

This trade-off is certainly popular. 
Chris Rutkowski, the marketing 
manager of Epson America, Inc., 
claims sales of 10,000 MX-80s a 
month. This figure seems to be limit- 
ed only by the capacity of the Japa- 
nese manufacturer to make and ship 
the machines. User groups for this 
printer have spontaneously sprouted 
around the country— unique for a pe- 
ripheral device! Let's take a look at 
this hot-selling printer and see what 
makes it so popular. 

The Epson MX-80 has two major 
attributes: good print quality and low 
price. The other features (which the 
MX-80 shares with some other dot 
matrix machines) include small size, 
low weight, low noise, great op- 
erational flexibility and mechanical 
simplicity. 

Too good to be true? It all depends 
on exactly what print quality you are 
willing to settle for. 

Print Quality 

Fig. 1 shows the quality and types 
of print available from the Epson 
MX-80. The machine uses a 9x9 dot 
matrix printhead for characters, and 
produces graphics in a 6x 12 dot for- 
mat. The lowercase characters have 
true descenders. The lowercase s 
probably shows the dots more clearly 
than any other character. Other low- 
ercase rounded characters such as 
the a and e also show the dots, but not 
as clearly. The s is made up of 14 
dots. In the double-strike mode, the 
paper is rolled up 1/216 inch and the 
character is printed again. The s is 
then made up of 28 dots slightly dis- 



50 Microcomputing, August 1981 



Various print styles are available on the MIX — QO - 
If different print styles are desired on one line or 
on one page, it is necessary to use BASIC PRINT 
statements to send the correct text and commands 
to the printer- 

Thi» is an example of double struck printing. It 
is a printing method which actually scrolls the paper 
vertically and then prints again to fill in the 
spaces between the dots. Some people like this mode, 
but others don't. 

Double striking can be combined with another mode 
called EJepH*mized Printing. 

A compressed lode is also available which gives 132 colums of print per line. This is very 

handy for soae statistical prograis which assuie you have an 80 coluen printer. With the HX-80, You DO J 

The EPSON MX-80 also has a graphics capability: 

Fig. 1. Sample printout showing MX-80 print styles. 



placed in the vertical axis. Some peo- 
ple find this print quality pleasing be- 
cause it smooths out the dots; others 
claim it is fuzzier, and prefer the sin- 
gle-strike mode. 

The different print styles are easy 
to use from BASIC, but they are 
much more difficult to mix on a sin- 
gle page when using a word-process- 
ing program. The most practical 
method of mixing print styles on one 
page is to write your document as 
BASIC "PRINT" statements. If you 
are using a word-processing program 
and want an entire page or document 
done in only one typeface, you must 
load BASIC, send an ASCII number 
out the I/O port to instruct the printer 
and then load your word-processing 
program. This could get a little cum- 
bersome with tape-based systems. It 
isn't bad with disk systems, as long as 
you remember to save the document 
you have been working on before 
you go to BASIC. 



Graphics 

The printer contains a graphics set 
essentially the same as the one used 
in the TRS-80 Model I. When it does 
graphics it doesn't simply copy the 
screen— it reproduces the figures in 
its ROM, based on received ASCII 
codes. If you have a computer with 
no graphics set, the printer will still 
respond to the codes. If you have a 
more elaborate graphics capability, 
the printer will still only produce 
what is in its own ROM. If you have a 
TRS-80 Model I, what you see is what 
you get (see Fig. 2). 

Connection 

The Epson MX-80 is easy to inter- 
face with most computer systems. It 
plugs directly into the Centronics 
parallel port. However, the standard 
Radio Shack parallel printer cable 
will not allow separation of the car- 
riage-return and line-feed signals. Ep- 
son says their special cable is needed 




YOU- . 



DECK 



■ 
■ 10 


• 7 


" Q 


P 4 


"q 


" 6 1 



• ■ ME * a ■ 



Fig. 2. Screen dump showing the opening hand of Instant Software's Cribbage program. 



to separate these signals if the printer 
is to do underlining and other special 
printing. 

If you don't need a separate CR and 
LF, the standard cable will work fine. 
This is a little hard to understand 
since each of these signals is a sepa- 
rate ASCII code, but the cables work 
as advertised. The Epson MX-80 
prints bidirectionally at a nominal 
speed of 80 characters per second. A 
machine connected through a paral- 
lel port has no problem in printing 
along with a 300 baud input. 

An optional RS-232C serial board is 
available for the printer. This inter- 
face is not quite so simple because it 
uses RS-232 pins 1 1 and 20 as clear- 
to-send lines. The Epson cannot hold 
or buffer serial data while it does a 
carriage return, line feed or form 
feed. If the computer does not stop 
transmitting, characters will be lost. 
When it needs some breathing room, 
the printer sets pins 11 and 20 to a 
low condition. 

This kind of interface requires 
more complex driver software than 
most RS-232C ports commonly pro- 
vide. Epson would probably have 
served the user better if they had in- 
cluded enough bytes of memory on 
the serial card to hold a few charac- 
ters during mechanical operations. 
An IEEE-488 standard interface is al- 
so available for use with Commodore 
microcomputers. 

Construction 

The Epson MX-80 has held up well 
under heavy use. The power supply 



Microcomputing, August 1981 51 






We're 

known 

for our 

fine print. 



♦or Y*»* ^"^ 

coo***" lou d»? * " ev^V 

Second »»** 

_, wn»n **** bor n ***** 

**•%! coon* •* c ^,7»v 
love* * y 



Epson. 



The type you get out of most printers you 
wouldn't send to your maiden aunt, much less 
use for your important correspondence. And up 
to now, in order to get a dot matrix hardcopy you 
could really call correspondence quality, you had 
to spend on the high side of a thousand bucks. 

Not any more. 

The Epson MX-80 challenges any dot matrix 
printer anywhere to match our type at our price. 
Or even come close. 

Our emphasized print mode gives you a tack- 
sharp, clean, easy-to-read 
face with true descenders — at 
a fraction of the price of daisy 
wheel printers. We give you a 
user-defined choice of twelve 
different weights and sizes of 
letters in 40, 80, 66 or 132 col- 
umns. We give you adjustable 
tractors so you can do any- 
thing from labels to memos to 
manuscripts. Fast and clean. 

But if you think print qual- 
ity is the only thing we have 




to sell, you're wrong. The MX-80 may be the 
most revolutionary printer to come out in the 
past ten years. 

For starters, it features the world's first dispos- 
able print head — after it's printed between 50 and 
100-million characters, just throw it away. A new 
one costs less than $30 and you can change it 
yourself with one hand. Plus, the MX-80 prints 
bidirectionally and 80 CPS with a logical seeking 
function to minimize print head travel time and 
maximize throughput. Finally — and this is the 

best part — you can buy an 

MX-80 right now for less than 

$650. 

And that's what we call a 

lot of fine print for the money. 



EPSON 

EPSON AMERICA, INC. 



23844 Hawthorne Boulevard • Torrance, CA 90505 • (213) 378-2220 



^116 



52 Microcomputing, August 1981 



transformer (no wall transformer!) 
runs cool. The printer has passed the 
FCC certification test for rf radiation 
as a class B (home computer) device, 
so it should not significantly interfere 
with local television or radio receiv- 
ers. 

The printhead is easy to replace 
and costs about $35. This is a fraction 
of the cost of printheads on compet- 
ing dot matrix printers. 

The tractor-feed mechanism is sim- 
ple but effective. Perforated paper 
tears cleanly along the top cover, but 
it takes a little practice to manually 
roll the paper back down so the top of 
the next page is aligned with the print- 
head. 

Documentation 

The MX-80 Printer User's Manual is 
a witty book which provides over 100 
pages of directions, hints and dia- 
grams. David A. Lien is the author, 
and he has used a very readable style 
which encourages MX-80 users to get 
the most out of the system. 

A separate service manual is also 
available— it is informative, but not 
as much fun to read. Most MX-80 
owners would benefit from having 
the service manual around. It con- 
tains clear instructions and exploded- 
view mechanical diagrams. Several 
trips to the local dealer for simple lu- 
brication or alignment can be avoid- 



ed through the use of the service 
manual. 

Psychology 

OK— this printer is reliable, easy to 
use and reasonably priced, but can it 
be used for real word processing? 
That question will raise an argument 
in many circles. 

Chris Rutkowski claims that peo- 
ple will soon expect dot matrix and 
tractor-fed paper with little perfora- 
tion marks around the edges. They 
will think you are inefficient and ex- 
travagant if you use single-fed sheets 
and high-priced printers. His vision 
of the future may be colored by his 
desire to keep his sales up, but it cer- 
tainly is true that the print quality of 
the MX-80 is good enough for many 
uses. 

If tractor-feed doesn't suit your 
needs, a newer version (the MX-80 
F/T) is now available with a pressure- 
feed capability (for $745). Don't con- 
fuse the MX-80 with its less capable 
brother, the MX-70. The 70's print 
face isn't nearly as pretty, and for 
some reason its operational reputa- 
tion is not as good. 

The MX-80 lists for $645, but you 
can find it advertised here in Micro- 
computing for under $500. At that 
price, you will have to judge if it is 
good enough to meet your word-pro- 
cessing needs. ■ 




Epson 's new MX- 100 is a 136-column wide printer in the normal 10 character per inch mode. In the com- 
pressed mode of 16.5 characters per inch it can print 233 characters on paper up to 15.5 inches wide. It 
can handle both pin feed and cut sheets. 



Epson's 
Newest Printer 

Epson has just added the 136-column 
MX- 100 to its series of technologically-ad- 
vanced dot matrix printers. 

The MX-100's predecessor, the MX-80, is 
now the largest-selling 80-column dot ma- 
trix printer in the world. 

The MX- 100 uses dot matrices ranging 
from 9x9tol8xl8to generate correspon- 
dence-quality printing in a total of 12 differ- 
ent character weights and sizes. The new 
printer also features Epson's Micro-Nine 
disposable printhead, and GRAFTRAX, a 
high resolution bit image graphics capability. 

Because the printer accepts paper up to 
15.5 inches wide, it is capable of printing up 
to 233 columns in the condensed print 
mode. It prints bidirectionally at 80 cps, 
with a logical seeking function to minimize 
printhead travel time and increase through- 
put. It comes standard with both a friction 
paper-feed platen and adjustable tractors on 
a removable tractor mechanism. 

The MX- 100 is currently available at a 
suggested retail price of $995. For more in- 
formation, contact Epson America, Inc., 
23844 Hawthorne Boulevard, Torrance, 
CA 90505. 



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Send for our FREE 14 page 
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utility, and business software. 




Aurora Software Associates 

P.O. Box 99553 

Cleveland, Ohio 44199 

(216)221-6981 



^193 



vSee List of Advertisers on page 194 



Microcomputing, August 1981 53 




STONE OF 
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APPLE 2 PLUS or APPLE 2 - A 
with Applesoft in ROM 
WORKS ON 3.2 OR 3.3 

Works on 1 or 2 drive systems 



042-0100 $29.95 



ALSO AVAIABLE FOR 
TRS-80 32K DISK Modal 1 



012-0100 $20.95 



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If you are successful in avoiding or conquer- 
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Your name and deeds will be recorded for posteri- 
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This successive approximation register helps you better understand analog-to-digital conversion. 



How to Cope 

With an Analog World 



By Theodore T. Tylaska 



Analog to digital converters (ADC) 
are absolute necessities when- 
ever a digital computer is used to 
sense analog signals in real-world ap- 
plications. 

There are several ways to convert 
an analog voltage into an equivalent 
digital number. The successive ap- 
proximation technique is the most 
popular, because it is a good compro- 
mise between speed and required 
hardware. The key control element 
in the successive approximation ADC 
is a medium-scale integration device 
called the successive approximation 
register (SAR). 

This design for a four-bit SAR con- 
structed from small-scale integrated 
circuits will help you better un- 
derstand the operation of this impor- 
tant register. Support components 
are added so that an operational suc- 
cessive approximation ADC can be 
constructed. LED indicators and sin- 
gle-step switches are included in the 
design so that the operation of the 
SAR can be observed for each clock 
pulse. 

Successive Approximation: 
An Overview 

For an overview of the principles of 
the successive approximation ADC, 
study the block diagram in Fig. 1. No- 
tice the ADC requires a digital to ana- 
log converter (DAC) plus other parts. 
Thus, the cost of an ADC is usually 
two to three times the cost of an 
equally accurate DAC itself. Suc- 
cessive approximation analog-to-digi- 
tal conversion is a more time-con- 
suming process than digital-to-analog 
conversion. The explanation of the 
SAR will clearly show that conver- 
sion time is a function of the number 
of bits of precision in the converter. 

The A/D conversion process begins 



CONVERSION 
COMPLETE 



CLOCK 



START 
CONVERSION - 



4-BIT SAR 
03 02 01 00 



DATA IN 



B3 
B2 
Bl 

BO 



. DIGITAL 
) WORD 

' OUT 



B3 B2 Bl BO 

4-BIT 

D/A CONVERTER 



ANALOG 

VOLTAGE 

IN 




COMPARATOR 



Fig. 1. Block diagram of four-bit successive ap- 
proximation AID converter. 



V )N =5.5V 



V FULL SCALE s 8 

7 

6 
5 
4 
3 
2 
I 



_ i. 



_i_ 



BIT 3 

♦o 

TIME 



BIT2 
♦i 



BIT I 
»2 



BITO CONVERSION 
COMPLETE 



Fig. 2. Successively approximating an analog 
voltage. 

upon receipt of a start conversion 
pulse. The successive approximation 
register sequentially turns on each 
weighted bit of the D/A converter to 
compare the voltage produced by 
that bit to the input voltage. The most 
significant bit (MSB), B3 of the D/A, is 
turned on first, and the output of the 
comparator is noted. 

If the D/A output voltage is less 
than the analog input voltage, the 
MSB is left on in the successive ap- 



proximation register; otherwise, the 
MSB is turned off in the SAR. The 
next MSB, B2, is turned on, and the 
summation of the voltages produced 
by B3 and B2 from the DAC is com- 
pared with the analog input voltage. 

If, for example, the output of the 
DAC exceeds the value of the input 
voltage, then bit Q2 is turned off in 
the SAR. The process continues until 
the least significant bit, BO, of the 
DAC is set, and a comparison is made 
between the input analog voltage to 
the ADC and the DAC output volt- 
age. If the ADC has n bits of preci- 
sion, there must be n comparisons 
made. 

This method is also called a binary 
approximation technique, because at 
each stage of the conversion a com- 
parison is made of one-half the re- 
maining difference to determine 
whether that bit is required in the ap- 
proximating voltage sum. Thus, the 
first step in the successive approxi- 
mation process must determine if the 
input exceeds V fs /2, where V fs is the 
full-scale input voltage of the ADC. 
The second step determines if V fs /2 2 
is needed, and the nth stage deter- 
mines if the weight of V fs /2 n is needed 
to approximate the input voltage. In 
general, n + 1 clock pulses are needed 
to perform the approximation. The 
first clock resets the SAR, and each 
succeeding clock determines the 
need for each successive bit. 

An example of approximating a giv- 
en voltage with a four-bit SAR feed- 
ing a DAC is shown in Fig. 2. The 
voltage to be approximated is 5.5 V. 
Assume the ADC full-scale output 
voltage is 8 V. The first approxima- 



Address correspondence to Theodore T. Tylaska, 
RFD 1, Box 230, Mystic, CT 06355. 



56 Microcomputing, August 1981 



tion sets bit 3, whose weight is 4 V. 
The second clock cycle attempts to 
set bit 2 with a weight of 2 V r but the 
resultant sum from the DAC is 6 V, 
which exceeds 5.5 V. Thus, bit 2 gets 



reset to a zero. At the third clock cy- 
cle, bit 1 is next turned on and the 
DAC adds 1 V to the sum which now 
totals to 4 + 1 = 5 V. Since this is less 
than 5.5 V, bit 1 remains set to 1. Bit 



♦5V *5V 

CFI 4 CF2 4 CF3 



♦ 5V 



^ 



CONTROL 
CLOCK 

INITIALIZE 



COMPARATOR 



DATA 
CLOCK 

INITIALIZE 



L 




IC lo 

C 

— o— 



12 



II 



L 



♦ 5V 




IC I b 

— cr 



13 



I 




IC2o 

-frr- 




cc 



CONTROL CIRCUIT 



B3 B3 



B2 



Bl 



^ 



2i 



J Q 

C 



15 



♦ 5V 



CFI- 



, — J J IC4o ^ X J IC4b 

CFI CF2 T 



♦ 5 




12 



♦ 5V 



J 

c 

K 



IC5b 



DATA REGISTER 



Fig. 3. 



BO 



ii 



adds 1/2 V to the sum to exactly equal 
the 5.5 V so bit remains set to 1 . The 
resulting digital word is (1011 ) 2 . 

Now that the function to be per- 
formed by the successive approxima- 
tion register has been examined, an 
implementation of the SAR can be 
surmised. If a four-bit SAR is being 
designed, the SAR must have some 
control method to selectively turn on 
or off each successive bit being tested. 
A four-bit shift register could fill the 
bill for control with a single "one" 
being shifted through the register. 
The presence of a "one" at a given 
stage of the shift register could signify 
that the corresponding bit in the SAR 
is being tested. The control circuit in 
Fig. 3 shows an arrangement for such 
a control shift register. 

This register is implemented out of 
74LS74 D-type flip-flops. The control 
register is started by an initialize 
pulse, which causes 1 to be directly 
set into the first stage flip-flop, IC1A, 
and to be directly set in the other 
four stages of the register. The last 
flip-flop, IC3A in the register, is used 
to hold the conversion complete con- 
dition. 




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Microcomputing, August 1981 57 



ANALOG VOLTAGE 
INPUT 




2 2K 



2 , ■ . COMPARATOR 

*OUT 




BO 



i *£ I 



-I2V 



DAC 



COMPARATOR 



OUTPUT LEDS 



:H>- 



♦ 5V 



♦ 5V 







1 


I t 






\ 


« 




iiO 




CC L START 


2 
3 


D 
IC70 

C 


S 12 


D 
IC7b 

C 




n 


8 r - 


PULSE 
















(J 


I 






1 


r 3 






CONTROL 










♦ 5\ 

t 


/ 



CLOCK 

START CONVERSION CIRCUIT 



SINGLE SW2 

CLOCK 

PULSE 
SWITCH 




CONTROL 
CLOCK 



£ _DATA 

CLOCK 



INITIALIZE 



STOP FREE 
RUNNING CLOCK 
SWI / SWITCH 



2 PHASE CLOCK GENERATOR 



Fig. 4. 



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Conversion complete occurs when 
the "one" preset into the first flip- 
flop has shifted into the fifth flip-flop. 
The OR gate IC8 holds the conver- 
sion complete condition in IC3A in 
the presence of continuous control 
clocks. At this time the result of the 
conversion can be read out of the data 
register. 

The data register is another set of 
four flip-flops which is used to hold 
the information as to whether or not 
each weighted bit of the DAC is need- 
ed to approximate the given input an- 
alog voltage. The data register is im- 
plemented by two 74LS76 J-K flip- 
flops as shown in Fig. 3. The initialize 
pulse sets bit 3 on, and turns off the 
remaining bits, B2, Bl and BO. Bit 3 is 
wired to the most significant bit of 
the DAC to generate the comparison 
voltage of V fs /2. 

The comparator output from IC11 
feeds the AND gate IC6 to determine 
whether a clear signal should be ap- 
plied to the K input of the flip-flop 
IC4A to reset it. If the comparator 
output shows that V fs /2 is less than 
the unknown applied voltage V in , 
then the comparator signal is low and 
flip-flop IC4A remains set with B3 
high. During the next data clock 
pulse, bit 2 from flip-flop IC4B is 
turned on to supply V fs /4 from the 
DAC output. 

Again, a comparison is made be- 
tween V in and the DAC output caused 
by the weighted sum of bit 3 and bit 
2. This process will continue until bit 
is summed into the accumulated 
output voltage of the DAC. A set of 
LEDs is connected to the data register 
outputs as shown in Fig. 4. 

Two Clock Phases 

The SAR is controlled by two clock 
phases called the control clock and 
the data clock. The clock generator 
IC9 is a 74LS123 dual monostable. 
The two monostables are cross-cou- 
pled to produce a square wave of pe- 
riod 2.4 us with the specified timing 
components. Closing switch SWI dis- 
ables IC9B and prevents the genera- 
tion of a continuous train of clock 
pulses. While SWI is closed, moving 
SW2 from position A to B and then 
back to position A will generate a sin- 
gle control clock and a single data 
clock pulse. Thus, you can single-step 
the SAR and observe on the LEDs the 
setting and clearing of each of the 
data flip-flops, depending on the re- 
sult of each voltage comparison. 

TJie timing diagram in Fig. 5 shows 



58 Microcomputing, August 1981 



the rising edge of the control clock to 
be delayed from the falling edge of 
the data clock. This delay is imple- 
mented by resistor R3, capacitor C3 
and IC10 to give a delay of 250 ns. 
Switch SW1 must be open and SW2 
must be in the A position for the clock 
to free run. IC8 serves as a clock buf- 
fer. 

The start circuit in Fig. 4 is imple- 
mented by two D-type flip-flops in 
package 1C7. The start pulse is a ris- 
ing edge, and it can be applied at any 
time. The timing diagram shows the 
start pulse setting flip-flop IC7A. At 
the next rising edge of the control 
clock, IC7B is set because its D input 
is 1. The initialize signal that sets the 
correct state in the control and data 
registers and also clears IC7A is gen- 
erated. On the next control clock ris- 
ing edge, IC7B goes to and removes 
the initialize signal. 

Control flip-flop CF1 remains high 



during control clock period 2. Since 
B3 is set, the DAC is making a trial 
comparison with its output at V fs /2. 
At the falling edge 2 of the data clock, 
the decision is made to keep B3 or to 
clear it. At the same time B2 is set be- 
cause CF1 is applied to the J input of 
IC4B while its K input is 0. 

At rising edge 3 of the control clock, 
CF1 is cleared and CF2 is set. This 
conditions the K input of B2 to give a 
clear signal or not, depending upon 
the result of the comparison of the 
DAC output with the input voltage 
V in . At falling edge 3 of the data clock, 
the decision is made to keep B2 set or 
clear it, and at the same time to set 
Bl. 

At rising edge 4 control flip-flop 
CF2 is cleared and CF3 is set to condi- 
tion data flip-flop Bl. This process 
continues until all the bits are tested, 
at which time the conversion com- 
plete (CC) signal on IC3A comes true. 



DATA CLOCK 
CONTROL CLOCK 

START FF IC7A (Q) 
INITIALIZE FF IC7B(Q) 



J L T 



r — i_n — l 



ii r 



i 



12 r 



i 



i 



_i — b r 

n — i rr~ 



— l^j-^ 
t n — u 

STOP CLOCK ^ 



CONTROL FF CF I | 

CONTROL FF CF2 

CONTROL FF CF3 

CONTROL FF CF4 
CONVERSION COMPLETE CC | 

DATA FF B3 | B3 TRIAL 

DATA FF B2 \ 

DATA FF Bl \ 

DATA FF BO \ 



-tJ- 



" V B3 DATA 



_/B2 TRIAL y B2 DATA 



J Bl TRIAL X Bl DATA* 



J BO TRIAL X BO DATA* 



Fig. 5. Timing diagram for successive approximation register. 




To have the converter operate contin- 
uously, simply wire the CC signal to 
the conversion start signal. 

A complete ADC can be built by 
adding a DAC and a comparator to 
the successive approximation regis- 
ter. The DAC shown in Fig. 4 is an 
eight-bit National DAC 0800LCN, 
which is wired to use only four bits. 
Resistor R5 is chosen to be 6k, so that 
2 mA of reference current flows into 
the V ref ( + ) pin. The selected refer- 
ence current determines the maxi- 
mum amount of current that can flow 
into the I ( -) pin. Thus, I ( -) of the 
DAC varies from mA with a digital 
input code of (111 1) 2 to 2 mA with a 
digital code of (0000) 2 placed on pins 
5 through 8. 

Resistor R4 is then chosen so that 
the voltage on pin 2, I ( - ), varies from 
+ 5 V to -5 V. A 5k resistor will be 
needed as 2 mA x 5k equals the 10 V 
drop needed across R4. The code pro- 
duced by the data register could be 
interpreted as straight binary for uni- 
polar input voltages, or as offset bi- 
nary for bipolar input voltages. The 
design in Fig. 4 will accept bipolar 
voltages of ±5 V. By connecting B3 
instead of B3 to the MSB LED light, 
the successive approximation regis- 
ter generates two's complement 
code. 

Conclusion 

It is easy to see that additional bits 
could be accommodated by adding 
more control and data flip-flops with 
the rest of the circuit remaining the 
same. Try building this circuit, which 
is very practical and can convert as 
fast as the DAC output can settle. 
You will end up with a good under- 
standing of how a successive approxi- 
mation register operates. ■ 



The successive approximation register. Note the position of the components on the prototype. 





Parts List 


C1,C2 


— 100 pF mica 


C3 


—.001 capacitor 


IC1,2,3,7 


-74LS74 


IC4.5 


-74LS76 


IC6 


— 74LS08 


IC8 


-74LS00 


IC9 


-74LS123 


IC10 


— 74LS14 


IC11 


-LM 311 


IC12 


-National DAC 0800LCN 


R1,R2 


-20k ohm 1/4 W 


R3 


-100 ohm 1/4 W 


R4,R5 


— 10k ohm trimpot 


R6 


-2.2k ohm 1/4 W 


SW1 


— SPST toggle switch 


SW2 


SPDT toggle switch 

_. . 



See List of Advertisers on page 194 



Microcomputing, August 1981 59 



This easy-to-build video system offers high-density graphics as well as programmable characters. 



Videographic 



By Joe Martinka 



My wife was studying for a col- 
lege degree in French, and had 
to write several papers every semes- 
ter. I had spent a delightful two years 
with a simple Heathkit terminal 
hooked up to my home computer, 
and decided it was time to provide 
her with one of its most valuable ser- 
vices: text editing and formatting. But 
first I needed upper/lowercase video 
display capability, something the old 
Heathkit terminal did not have. 
I was willing to consider the easy 



but costly option of buying a video 
display ready to go. But after scan- 
ning the microcomputing magazines, 
I soon realized that this option would 
be too expensive. Consider that I in- 
cluded as necessary specifications: 

• Programmable special characters. 
An indispensable feature, since most 
of her text processing would be in 
French, and would require special ac- 
cents and the like. 

• Eighty characters per display row, 
24 lines on screen, and a versatile 8 




Photo 1 . Overall view of the author's system. Involves a home-brew system boasting a 4 MHz Z-80A pro- 
cessor, 48K RAM, North Star disk system and the Videographic video interface. The large keyboard to the 
left houses a one-of-a kind Selectric interface for hard-copy output. The Selectric typewriter itself is not 
shown. 



by 12 character matrix. 

• Compatible with 4 MHz processors. 

• Memory- mapped video for ease of 
screen update and programming. 

• Programmable cursor control and 
reverse video capability. 

• Graphics capability. To make the 
board useful for my own games and 
display needs, I had to be careful that 
limited hardware capabilities would 
not confine my imagination. I wanted 
good resolution— 256 by 256 would 
do nicely for games, graphs and chart 
programs. 

A reasonably priced commercial 
video board would satisfy only some 
of the above specifications. Some 
were tailored only to a certain proces- 
sor, some were too slow and some 
had no graphics at all. I then decided 
to do what any true-blooded comput- 
er lover would do— build one myself. 
Thus, Videographic was born. 

The advantages I gained by design- 
ing it were satisfying. I was able to ac- 
commodate my S-100 bus running a 4 
MHz Z-80 microprocessor. See Photo 
1. I could shift the entire mode of the 
video board from a character-orient- 
ed display to a full-graphics mode 
with a single input-output command. 
I used a new and exciting program- 
mable video-display-controller inte- 
grated circuit, affording excellent 
versatility: as my needs change, I can 
change the mode of the display sim- 
ply by reprogramming the video dis- 

Address correspondence to Joe Martinka, do 
Microcomputing. 



60 Microcomputing, August 1981 



play chip. Lastly, I made use of a 
spare Godbout Econoram 8K static 
memory board that reduced my costs 
even further. 

Videographic's abilities are sum- 
marized in Table 1. It is easy to build 
this board, or one like it, emphasizing 
your own personal needs. The rest of 
this article will show you how. 

Theory of Operation 

As the block diagram in Fig. 1 indi- 
cates, Videographic is a relatively 
simple concept built around the Mo- 
torola MC6845 video chip. Originally 
designed for the 6800 and 6502 mi- 
croprocessors, the MC6845 can be 
made to work with the faster Z-80A. 
The static RAM memory is shared be- 
tween the 6845 and the host proces- 
sor. The 6845 uses the memory con- 
tinually as the source of information 
for TV screen updates, while the host 
processor can access the same mem- 
ory as easily as it can regular memory. 
Hence the label: memory-mapped 
video. 

While I use the Godbout board, 
there is plenty of room on the main 
board for your own memory chips 
(Photos 2 and 3). By using the popular 
21 14 static RAM chip, you can imple- 
ment 8K memory using only one- 
eighth of the chips you see on the 
Godbout board. I used the extra 



board because I already owned it. 
You could use existing memory, too. 
The changes you would have to make 
to the circuit are negligible. Choose 
the way that is easiest for you. 

The video display chip, the Motor- 
ola MC6845, performs all the neces- 
sary video timing and refresh func- 
tions needed to produce a truly inex- 
pensive high-density display. It can 
generate timing for almost any alpha- 
numeric screen density, from 40 x 12 
to 80x24. It is powered by a single 
± 5 V supply, offers hardware scroll- 
ing by character, line or page, as well 
as various cursor modes and light pen 
capability. The 6845 can address up 
to 16K of memory. (In Videographic, 
I make use of half that amount.) 

The reader should obtain the tech- 
nical notes on the 6845 from a local 
Motorola office before using the chip 
in his own application. A 20-page 
booklet is available describing the op- 
eration and programming considera- 
tions of the 6845. The versatility built 
into the video display processor is ex- 
plained in detail, and is available 
from the address listed in Reference 1 . 

The 12.440 MHz clock provides the 
basic timing and "dot clock" for the 
entire display. The 12.440 MHz sig- 
nal is used to clock the shift register 
that feeds dots to the video combiner 
circuit while in the character mode. 



(One- half of that rate clocks the dots 
out in the graphics mode.) This dot 
clock frequency is divided by eight to 
provide the character clock, and is 
the signal that controls the transfer of 
characters between portions of Vid- 
eographic. 

A programmable 5-V 2Kx8 
EPROM, the 2716, is used as the 
character generator. Using this chip, 
you can literally create your own 
character set. I created mine using an 
8 by 12 grid on which I had placed 
pennies to form the style I liked, 
which included descenders and un- 
usual French alphabetics. (By squint- 
ing at the grid, you can imagine what 
the letter would look like on the 
screen.) Fig. 2 shows the dollar sign 
character being formed. The contents 
of my EPROM are shown in Listing 1 . 
The characters at the left of the listing 
are only typewriter references and do 
not show the actual shape, as the typ- 
ical character display in Photo 4 does. 

You can avoid the hassle of EPROM 
programming your own custom char- 
acters if you can be satisfied with a 
factory-programmed character set. 
Unless you can obtain the use of a 
programmer, it would be significant- 
ly more economical to use popular 
chips such as the 6072 or the 
MCM66750, which are no more than 
one-chip ROMs. A 2716 EPROM or a 



SHARED STATIC 
RAM MEMORY 



ADDRESS REGISTER BUS 



<*t 



8K 

MEMORY 

BLOCK 



c 



ROW 
ENABLE 



MAII-MAI3 



BUFFER 



BUFFER 



r> 



SELECT LOGIC 



o U 



i w 



CONTROL 
SIGNALS 



VIDEOGRAPHIC CIRCUITS 



ROW 



<~L 



BUFFER 



ROW 
MULTI- 
PLEXER 



7*; 



<-— o 



^ 



ADDRESSES 
RERESM 



LATCH 



CONTROL 
SIGNALS 



MISCELLANEOUS 
CONTROLS 



JL. 



A 



O 



CONTROL 
SIGNALS 



ro 



CHARACTER 
CLOCK 



♦ N 



6845 
VIDEO 
CHIP 



A*> 



BLANKING 



DOT 
CLOCK 



CLOCK 
TIMING 



CRYSTAL 



SYNC PULSES 



CURSOR 



LIGHT 
PEN 



ROW 
ADDRESS 



BUFFER 



VIDEO 
COMBINER 



VIDEO 
SIGNAL 



TV 



CHAR 

GEN 

2516 



D 



BYPASS 
IC 







SHIFT 
REGISTER 



LIGHT 



CHARACTER 

GRAPHIC 

MODE 



{^ 



ADDR DATA DATA PRDY AIOAI2 

A0-A9 OUT IN 










PRDY A0-A8 



DATA 
IN /OUT 



COMPUTER BUS 



Fig. 1. Block diagram of the Videographic circuit based around the Motorola MC6845 video display controller. 



Microcomputing, August 1981 61 



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factory-programmed ROM will work 
equally well in the character genera- 
tor spot with only minor socket-wir- 
ing changes. 

At a given value of row count, the 
6845 will put out the addresses of a 
series of 80 characters of refresh 
memory. Then it increments the row 
count and repeats the series of 80 ad- 
dresses to the programmed total of 12 
times, to paint all rows of the dots on 
the screen for the whole character 
line. Then the row count resets to 
zero and the process is repeated for 
the next line. You program the 6845 
to output the vertical and horizontal 
sync pulses at any specified moment 



in the timing so that the video chip 
will adapt to nearly any monitor or 
modified TV. This feature of the 6845 
lets you center the display by merely 
changing one or two software bytes. 

Videographic can reverse any char- 
acter to black-on-white with bit 7— 
the most significant bit— set to 1. This 
feature can be used to highlight blocks 
of text, or create a screen that looks 
more like words on paper. 

The 6845 accesses the shared mem- 
ory through a multiplexer, which can 
be thought of as a 13-pole, two-posi- 
tion switch. The position of this 
switch is such that the memory is 
normally driven by this 6845 update 



Listing 1 . A hexadecimal dump of the 


EPROM character generator that I use in 


Videographic to pro- 


duce a customized display in the character mode. The first two digits c 


)f the PROM address is conve- 


niently the ASCII equivalent < 


of the character. 




















VIDEO 


PROM 






Rows o 


f character dots 














CHAR 


ADDR 
000 





1 


2 


3 


4 


5 6 


7 


8 


9 


L0 . 


LI 








00 


00 


00 


00 


00 


00 00 


00 


00 


00 


00 


00 


00 


00 


00 00 


CNTL-A 


010 


00 


00 


00 


00 


00 


00 00 


00 


00 


00 


00 


00 


00 


00 


00 00 


CNTL-B 


020 


00 


00 


00 


00 


00 


00 00 


00 


00 


00 


00 


00 


00 


00 


00 00 


CNTL-C 


030 


00 


00 


00 


00 


00 


00 00 


00 


00 


00 


00 


00 


00 


00 


00 00 


CNTL-D 


040 


00 


00 


00 


00 


00 


00 00 


00 


00 


00 


00 


00 


00 


00 


00 00 


CNTL-E 


050 


00 


00 


00 


00 


00 


00 00 


00 


00 


00 


00 


00 


00 


00 


00 00 


CNTL- F 


060 


00 


00 


00 


00 


00 


00 00 


00 


00 


00 


00 


00 


00 


00 


00 00 


CNTL-G 


070 


00 


00 


00 


00 


00 


00 00 


00 


00 


00 


00 


00 


00 


00 


00 00 


CNTL-H 


080 


00 


00 


00 


00 


00 


00 00 


00 


00 


00 


00 


00 


00 


00 


00 00 


CNTL- I 


090 


00 


00 


00 


00 


00 


00 00 


00 


00 


00 


00 


00 


00 


00 


00 00 


CNTL-J 


0A0 


00 


00 


00 


00 


00 


00 00 


00 


00 


00 


00 


00 


00 


00 


00 00 


CNTL-K 


0B0 


00 


00 


00 


00 


00 


00 00 


00 


00 


00 


00 


00 


00 


00 


00 00 


CNTL-L 


oco 


00 


00 


00 


00 


00 


00 00 


00 


00 


00 


00 


00 


00 


00 


00 00 


CNTL-M 


0D0 


00 


00 


00 


00 


00 


00 00 


00 


00 


00 


00 


00 


00 


00 


00 00 


a 


0E0 


10 


28 


44 


IE 


22 


42 42 


46 


3A 


00 


00 


00 


00 


00 


00 00 


• 


0F0 


10 


28 


44 


3C 


42 


42 7E 


40 


3E 


00 


00 


00 


00 


00 


00 00 


I 


100 


10 


28 


44 


30 


10 


10 10 


10 


10 


00 


00 


00 


00 


00 


00 00 





110 


10 


28 


44 


3C 


42 


42 42 


42 


3C 


00 


00 


00 


00 


00 


00 00 


a 


120 


10 


28 


44 


42 


42 


42 42 


42 


3E 


00 


00 


00 


00 


00 


00 00 


I 


130 


00 


66 


00 


IE 


22 


42 42 


46 


3A 


00 


00 


00 


00 


00 


00 00 


l 


140 


00 


66 


00 


3C 


42 


42 7E 


40 


3E 


00 


00 


00 


00 


00 


00 00 


i 


150 


00 


66 


00 


30 


10 


10 10 


10 


10 


00 


00 


00 


00 


00 


00 00 


o 


160 


00 


66 


00 


3C 


42 


42 42 


42 


3C 


00 


00 


00 


00 


00 


00 00 


U 


170 


00 


66 


00 


42 


42 


42 42 


42 


3E 


00 


00 


00 


00 


00 


00 00 


f 


180 


00 


00 


00 


3C 


42 


40 40 


42 


3C 


10 


oc 


18 


00 


00 


00 00 


190 


3C 


24 


3C 


00 


00 


00 00 


00 


00 


00 


00 


00 


00 


00 


00 00 


§ 


1A0 


1C 


20 


40 


20 


1C 


L4 1C 


80 


40 


40 


38 


00 


00 


00 


00 00 




1B0 


00 


00 


00 


00 


00 


00 00 


00 


00 


00 


00 


00 


00 


00 


00 00 


e 


1C0 


60 


18 


04 


3C 


42 


42 7E 


40 


3E 


00 


00 


00 


00 


00 


00 00 


e 


1D0 


06 


18 


20 


3C 


42 


42 7E 


40 


3E 


00 


00 


00 


00 


00 


00 00 


1 


1E0 


60 


18 


04 


IE 


22 


42 42 


46 


3A 


00 


00 


00 


00 


00 


00 00 


a 


1F0 


60 


18 


04 


42 


42 


42 42 


42 


3E 


00 


00 


00 


00 


00 


00 00 


Sf*4*. 


200 


00 


00 


00 


00 


00 


00 00 


00 


00 


00 


00 


00 


00 


00 


00 00 


! 


210 


00 


10 


10 


10 


10 


10 10 


00 


10 


00 


00 


00 


00 


00 


00 00 


M 


220 


28 


28 


00 


00 


00 


00 00 


00 


00 


00 


00 


00 


00 


00 


00 00 


* 


230 


00 


28 


28 


FE 


28 


FE 2 8 


28 


00 


00 


00 


00 


00 


00 


00 00 


$ 


240 


28 


7E 


A8 


A8 


7C 


2 A 2A 


FC 


28 


00 


00 


00 


00 


00 


00 00 


% 


250 


00 


42 


E4 


48 


10 


24 4E 


84 


00 


00 


00 


00 


00 


00 


00 00 


& 


260 


70 


88 


88 


50 


20 


52 8C 


8C 


72 


00 


00 


00 


00 


00 


00 00 


• 


270 


18 


08 


10 


00 


00 


00 00 


00 


00 


00 


00 


00 


00 


00 


00 00 


( 


280 


02 


04 


08 


08 


08 


08 08 


04 


02 


00 


00 


00 


00 


00 


00 00 


) 


290 


40 


20 


10 


10 


10 


10 10 


20 


40 


00 


00 


00 


00 


00 


00 00 


* 


2A0 


00 


10 


54 


38 


FE 


38 54 


10 


00 


00 


00 


00 


00 


00 


00 00 


+ 


2B0 


00 


00 


10 


10 


7C 


10 10 


00 


00 


00 


00 


00 


00 


00 


00 00 


i 


2C0 


00 


00 


00 


00 


00 


00 00 


00 


30 


10 


20 


00 


00 


00 


00 00 


— 


2D0 


00 


00 


00 


00 


7C 


00 00 


00 


00 


00 


00 


00 


00 


00 


00 00 


• 


2E0 


00 


00 


00 


00 


00 


00 00 


00 


30 


00 


00 


00 


00 


00 


00 00 


/ 


2F0 


00 


02 


04 


08 


10 


20 40 


80 


00 


00 


00 


00 


00 


00 


00 00 





300 


38 


44 


86 


8A 


92 


A2 C2 


44 


38 


00 


00 


00 


00 


00 


00 00 


1 


310 


10 


30 


50 


10 


10 


10 10 


10 


7C 


00 


00 


00 


00 


00 


00 00 


2 


320 


7C 


82 


02 


04 


18 


20 40 


80 


E 


00 


00 


00 


00 


00 


00 00 


3 


330 


7E 


04 


08 


10 


3C 


02 02 


82 


7C 


00 


00 


00 


00 


00 


00 00 


4 


340 


08 


18 


28 


48 


FE 


08 08 


08 


08 


00 


00 


00 


00 


00 


00 00 


5 


350 


FC 


80 


80 


80 


FC 


02 02 


82 


7C 


00 


00 


00 


00 


00 


00 00 


6 


360 


7C 


82 


80 


80 


FC 


82 82 


82 


7C 


00 


00 


00 


00 


00 


00 00 


7 


370 


7E 


42 


02 


04 


08 


10 10 


10 


10 


00 


00 


00 


00 


00 


00 00 


8 


380 


7C 


82 


82 


82 


7C 


82 82 


82 


7C 


00 


00 


00 


00 


00 


00 00 


9 


390 


7C 


82 


82 


82 


7E 


02 02 


82 


7C 


00 


00 


00 


00 


00 


00 00 


: 


3A0 


00 


00 


00 


18 


00 


00 18 


00 


00 


00 


00 


00 


00 


00 


00 00 


; 


3B0 


00 


00 


00 


00 


18 


00 00 


18 


08 


10 


00 


00 


00 


00 


00 00 


< 


3C0 


00 


04 


08 


10 


20 


10 08 


04 


00 


00 


00 


00 


00 


00 


00 00 
lMor t - . 



62 Microcomputing, August 1981 



DOWN-TO-EARTH PRICES ON 
OUT-OF-THIS-WORLD PERSONAL 

COMPUTERS AND COMPONENTS 



Look at this! 




Ohio Scientific 
Superboard II 




• It's the first complete computer 
system on a board. 

• Superboard II uses the ultra 
powerful 6502 Microprocessor 

• 8K Microsoft BASIC-in-ROM 

• 4K static RAM on board, 
expandable to 8K 

• Full 53-key keyboard, with upper 
and lower case. Plus user 
expandability. 

• Video interface and audio 
cassette interface. 

The Ohio Scientific Superboard II at 
$299 — in today's economy — has 
got to be the best buy by far. It will 
entertain you with spectacular 
graphics made possible by its ultra 
high resolution graphics and super 
fast BASIC. It will help you in school 
or industry, as an ultra powerful 
scientific calculator. Advanced 
scientific functions and a built-in 
"immediate" mode allow you to 
solve complex problems without 
programming. 

The Superboard II can be 
expanded economically, for business 
uses, or to remotely control your 
home appliances and security. Even 
communicate with other computers. 

Read what's been written 
about Superboard II: 

"We heartily recommend Super- 
board II for the beginner who wants 
to get into microcomputers with a 
minimum cost. A real computer 
with full expandability." 

—POPULAR ELECTRONICS. MARCH 1979 

"The Superboard II is an excellent 
choice for the personal computer 
enthusiast on a budget." 

—BYTE, MAY 1979 



Look at these easy hardware prices: 

610 Board For use with Superboard II and Challenger 1 P. 

8K static RAM. Expandable to 24K or 32K system total. 

Accepts up to two mini-floppy disk drives. Requires + 5V 

@4.5 amps. $ 298 

Mini-Floppy Disk Drive Includes Ohio Scientific's PICO DOS 
software and connector cable. Compatible with 610 
expander board. Requires + 1 2V @1 .5 amps and + 5V @ 
0.7 amps. [Power supply & cabinet not included.] 

630 Board Contact us for important details. 

AC-3P 12" combination black and white TV/video monitor. 159 

4KP 4K RAM chip set. 79 

PS-005 5V 4.5 amp power supply for Superboard II. 45 

PS-003 1 2V power supply for mini-floppies. 45 

RF Modulator Battery powered UHF Unit. 35 

CS-900B Metal case for single floppy disk drive and power 

supply. [While stock lasts.) 49 

AC-12P Wireless remote control system. Includes control 
console, two lamp modules and two appliance modules, for 
use with 630 board. 175 

AC-17P Home security system. Includes console, fire 

detector, window protection devices and door unit for use 

with 630 board. 249 

C1P Sams C1 P Service manual 8 

C4P Sams C4P Service manual 16 

C3 Sams Challenger III manual 40 

Ohio Scientific and independent suppliers offer hundreds of programs for the 

Superboard II, in cassette and mini-floppy form. 



Freight Policies All orders of $100 or more are 
shipped freight prepaid. Orders of less than $1 00 please add 
$4.00 to cover shipping costs. Ohio residents add 5.5% Sales Tax. 



m 



Hours: Call Monday thru Friday 
8:00 AM to 5:00 PM E.D.T. 
TOLL FREE: 1 800 321 5805 



Guaranteed Shipment 

Cleveland Consumer Computers S. Components 
guarantees shipment of computer systems 
within 48 hours upon receipt of your order. 
Our failure to ship within 48 hours 
entitles you to 835 of software, FREE. 



TO Order: Or to get our free catalog CALL 1-800-321-5805 TOLL FREE. Charge your 
order to your VISA or MASTER CHARGE account. Ohio residents call: [21 6] 464-8047. 
Or write, including your check or money order, to the address listed below. 

CLEVELAND CONSUMER 
COMPUTERS & COMPONENTS 

P.O. Box 46627 
Cleveland, Ohio 44146 




I Order Form: 

I 

I 

I 

I 
I 

L 



CLEVELAND CONSUMER P.O. Box 46627 

COMPUTERS & COMPONENTS Cleveland, Ohio 44146 

□ Superboard II $299. □ RF Modulator $35. 
a 61 Board $298. □ AC-3P 1 2 " BAA/ Monitor $1 59. 

□ Mini-Floppy Disk Drive $299. DC1P Sams Manual $8. 
[Attach separate sheet for other items.] 

NAME 

ADDRESS: 

CITY: 

PHONE: 



STATE: 



ZIP: 



Payment by: VISA 

Credit Card Account #. 



MASTER CHARGE 



MONEY ORDER 



Interbank #[Master Charge} 



Expires 

TOTAL CHARGED OR ENCLOSED $ fOh.o Residents add 6.5% Sales Tax] 

Orders of less than $100. please add $4.00 to cover shipping costs. Orders will be accepted from U.S. and 
Canada only All prices quoted are U.S.. date of publication, standard UPS shipping FOB the factory. 



K 



^See List of Advertisers on page 194 



Microcomputing, August 1981 63 



Listing 1 



I I continued. 
































= 


3D0 


00 


00 


00 


3C 


00 


3C 


00 


00 


00 


00 


00 


00 


00 


00 


00 


00 


> 


3E0 


00 


20 


10 


08 


04 


08 


10 


20 


00 


00 


00 


00 


00 


00 


00 


00 


? 


3F0 


3C 


42 


42 


04 


08 


10 


10 


00 


10 


00 


00 


00 


00 


00 


00 


00 


e 


400 


00 


3C 


42 


9A 


AA 


AA 


9C 


40 


3C 


00 


00 


00 


00 


00 


00 


00 


A 


410 


38 


44 


82 


82 


FE 


82 


82 


82 


82 


00 


00 


00 


00 


00 


00 


00 


B 


420 


FC 


42 


42 


42 


7E 


42 


42 


42 


FC 


00 


00 


00 


00 


00 


00 


00 


C 


430 


3C 


82 


80 


80 


80 


80 


80 


82 


7C 


00 


00 


00 


00 


00 


00 


00 


D 


440 


FC 


42 


42 


42 


42 


42 


42 


42 


FC 


00 


00 


00 


00 


00 


00 


00 


E 


450 


FE 


80 


80 


80 


F8 


80 


80 


80 


FE 


00 


00 


00 


00 


00 


00 


00 


F 


460 


FE 


80 


80 


80 


F8 


80 


80 


80 


80 


00 


00 


00 


00 


00 


00 


00 


G 


470 


7C 


82 


80 


80 


80 


8E 


82 


82 


7E 


02 


00 


00 


00 


00 


00 


00 


H 


480 


82 


82 


82 


82 


FE 


82 


82 


82 


82 


00 


00 


00 


00 


00 


00 


00 


I 


490 


7C 


10 


10 


10 


10 


10 


10 


10 


7C 


00 


00 


00 


00 


00 


00 


00 


J 


4A0 


3E 


08 


08 


08 


08 


08 


88 


88 


70 


00 


00 


00 


00 


00 


00 


00 


K 


4B0 


82 


84 


88 


90 


E0 


90 


88 


84 


82 


00 


00 


00 


00 


00 


00 


00 


L 


4C0 


80 


80 


80 


80 


80 


80 


80 


80 


FE 


00 


00 


00 


00 


00 


00 


00 


M 


4D0 


82 


C6 


AA 


92 


92 


82 


82 


82 


82 


00 


00 


00 


00 


00 


00 


00 


N 


4E0 


82 


C2 


A2 


92 


8A 


86 


82 


82 


82 


00 


00 


00 


00 


00 


00 


00 





4F0 


7C 


82 


82 


82 


82 


82 


82 


82 


7C 


00 


00 


00 


00 


00 


00 


00 


P 


500 


FC 


82 


82 


82 


FC 


80 


80 


80 


80 


00 


00 


00 


00 


00 


00 


00 


Q 


510 


7C 


82 


82 


82 


82 


82 


8A 


8A 


8C 


04 


02 


00 


00 


00 


00 


00 


R 


520 


FC 


82 


82 


82 


FC 


90 


88 


84 


82 


00 


00 


00 


00 


00 


00 


00 


S 


530 


7C 


82 


80 


40 


38 


04 


02 


82 


7C 


00 


00 


00 


00 


00 


00 


00 


T 


540 


FE 


92 


10 


10 


10 


10 


10 


10 


10 


00 


00 


00 


00 


00 


00 


00 


U 


550 


82 


82 


82 


82 


82 


82 


82 


82 


7E 


00 


00 


00 


00 


00 


00 


00 


V 


560 


82 


82 


82 


82 


82 


82 


44 


28 


10 


00 


00 


00 


00 


00 


00 


00 


W 


570 


82 


82 


82 


92 


92 


92 


92 


BA 


44 


00 


00 


00 


00 


00 


00 


00 


X 


580 


82 


82 


44 


28 


10 


28 


44 


82 


82 


00 


00 


00 


00 


00 


00 


00 


Y 


590 


82 


82 


44 


28 


10 


10 


10 


10 


10 


00 


00 


00 


00 


00 


00 


00 


Z 


5A0 


FE 


02 


04 


08 


7C 


20 


40 


80 


FE 


00 


00 


00 


00 


00 


00 


00 


I 


5B0 


3C 


20 


20 


20 


20 


20 


20 


20 


3C 


00 


00 


00 


00 


00 


00 


00 


\ 


5C0 


00 


80 


40 


20 


10 


08 


04 


02 


00 


00 


00 


00 


00 


00 


00 


00 


] 


5D0 


3C 


04 


04 


04 


04 


04 


04 


04 


3C 


00 


00 


00 


00 


00 


00 


00 


* 


5E0 


00 


10 


38 


54 


10 


10 


10 


10 


00 


00 


00 


00 


00 


00 


00 


00 




5F0 


00 


00 


00 


00 


00 


00 


00 


00 


00 


00 


IE 


00 


00 


00 


00 


00 


I 


600 


FE 


82 


92 


8A 


FE 


8A 


92 


82 


FE 


00 


00 


00 


00 


00 


00 


00 


a 


610 


00 


00 


00 


IE 


22 


42 


42 


46 


3A 


00 


00 


00 


00 


00 


00 


00 


b 


620 


40 


40 


40 


58 


64 


42 


42 


62 


5C 


00 


00 


00 


00 


00 


00 


00 


c 


630 


00 


00 


00 


3C 


42 


40 


40 


42 


3C 


00 


00 


00 


00 


00 


00 


00 


d 


640 


02 


02 


02 


1A 


26 


42 


42 


46 


3A 


00 


00 


00 


00 


00 


00 


00 


e 


650 


00 


00 


00 


3C 


42 


42 


7E 


40 


3E 


00 


00 


00 


00 


00 


00 


00 


f 


660 


OC 


12 


10 


10 


38 


10 


10 


10 


10 


00 


00 


00 


00 


00 


00 


00 


g 


670 


00 


00 


00 


LA 


26 


42 


42 


46 


3 


02 


42 


3C 


00 


00 


00 


00 


h 


680 


40 


40 


40 


58 


64 


44 


44 


44 


44 


00 


00 


00 


00 


00 


00 


00 


i 


690 


00 


10 


00 


30 


10 


10 


10 


10 


10 


00 


00 


00 


00 


00 


00 


00 


• 


6A0 


00 


04 


00 


04 


04 


04 


04 


04 


04 


04 


44 


38 


00 


00 


00 


00 


k 


6B0 


40 


40 


40 


44 


48 


70 


48 


44 


42 


00 


00 


00 


00 


00 


00 


00 


1 


6C0 


30 


10 


10 


10 


10 


10 


10 


10 


10 


00 


00 


00 


00 


00 


00 


00 


m 


6D0 


00 


00 


00 


A4 


DA 


92 


92 


92 


92 


00 


00 


00 


00 


00 


00 


00 


n 


6E0 


00 


00 


00 


5C 


62 


42 


42 


42 


42 


00 


00 


00 


00 


00 


00 


00 


o 


6F0 


00 


00 


00 


3C 


42 


42 


42 


42 


3C 


00 


00 


00 


00 


00 


00 


00 


p 


700 


00 


00 


00 


58 


64 


42 


42 


62 


5C 


40 


40 


40 


00 


00 


00 


00 


q 


710 


00 


00 


00 


LA 


26 


42 


42 


46 


3A 


02 


02 


02 


00 


00 


00 


00 


r 


720 


00 


00 


00 


1C 


52 


60 


40 


40 


40 


00 


00 


00 


00 


00 


00 


00 


s 


730 


00 


00 


00 


3C 


42 


30 


OC 


42 


3C 


00 


00 


00 


00 


00 


00 


00 


t 


740 


00 


10 


10 


7C 


10 


10 


10 


12 


OC 


00 


00 


00 


00 


00 


00 


00 


u 


750 


00 


00 


00 


42 


42 


42 


42 


42 


3E 


00 


00 


00 


00 


00 


00 


00 


V 


760 


00 


00 


00 


44 


44 


44 


44 


28 


10 


00 


00 


00 


00 


00 


00 


00 


w 


770 


00 


00 


00 


82 


82 


92 


92 


92 


e 


00 


00 


00 


00 


00 


00 


00 


X 


780 


00 


00 


00 


42 


24 


18 


18 


24 


42 


00 


00 


00 


00 


00 


00 


00 


y 


790 


00 


00 


00 


44 


44 


44 


44 


4C 


34 


04 


44 


38 


00 


00 


00 


00 


z 


7A0 


00 


00 


00 


7E 


04 


08 


10 


20 


7E 


00 


00 


00 


00 


00 


00 


00 


— . 


7B0 


00 


00 


00 


00 


FF 


00 


00 


00 


00 


00 


00 


00 


00 


00 


00 


00 


\ 


7C0 


10 


10 


10 


10 


10 


10 


10 


10 


10 


10 


10 


10 


10 


10 


10 


10 




7D0 


00 


00 


00 


00 


00 


00 


00 


00 


00 


FF 


00 


00 


00 


00 


00 


00 


m 


7E0 


FF 


FF 


FF 


FF 


FF 


FF 


FF 


FF 


FF 


FF 


FF 


FF 


FF 


FF 


FF 


FF 




7F0 


00 


00 


00 


00 


00 


00 


00 


00 


00 


00 


00 


00 


00 


00 


00 


00 



TYPICAL CHARACTER LOAD FOR $ 



ROW 

O 

I 

2 

3 

4 

5 

6 

7 

8 

9 

10 

I I 





GRAPHIC FONT 


















X 
















X 


• 














X 


• 














X 
















X 














• 


X 














• 


X 
















X 
















X 
















X 
















X 
















X 



BINARY 



HEX 



t_ 



= OOIOIOOO = 28 

■ O M I i I 10 ■ 7E 

= IOIOI OOO = A8 

= IOIOI OOO = A8 

= O I I I I I OO = 7C 

= OOIOI 01 O = 2A 

= OOIOI 01 O = 2A 

= I I I I I I OO = FC 

= OO IOI OOO = 28 

= OOOOOOOO = OO 

■ OOOOOOOO ■ OO 

■ OOOOOOOO = OO 



ALWAYS LEFT BLANK FOR CHARACTER 
TO CHARACTER SPACING 



EPROM 

THE ASCII CODE FOR 
$ IS 24 

SO, IN EPROM ADDRESS 

0240, PUT 28 (ROW O) 

0241, PUT 7E (ROW I) 

0242, PUT A8 ( ROW2) 

\ ETC TO \ 

0449, PUT OO ( ROW 9) 
044A, PUT OO ( ROW 10) 
044B, PUT OO (ROW II) 



Fig. 2. Creating a character for your custom character generator. I used pennies to form the shape I want- 
ed, then formed the eight-bit bytes across each row for a total of 12 bytes. The 6845 will call for this pattern 
row by row until the character is completely formed on the TV screen. 



address. When the control logic on 
the memory board sees that the pro- 
cessor is requesting a valid S-100 bus 
address, it generates the BDSEL sig- 
nal. The multiplexer switches the ad- 
dress from the processor to the mem- 
ory instead of the address normally 
supplied by the 6845. 

The processor can then read or 
write to that location. The memory 
output is probably not correct for the 
display at that moment, so a segment 
of a different character is substituted 
for the correct one, producing a snow 
effect if extensive updates are being 
performed. The snow can be elimi- 
nated by allowing the processor to ac- 
cess the shared memory only when 
the display is in the blanking cycle 



GRAPHICS 
PAGE 



GRAPHICS 
PAGE 



f\ An 


248 


\J\A\ 


DOTS 


256 




DOTS 





14 



\6S\fcfe 



GRAPHIC BYTES 



64 GROUPS 
OF 4 



124 

GROUPS 
OF 2 



GRAPHICS 
BYTE 



2 DOTS 



4 DOTS 



EXAMPLE. 




IS STORED AS 
OIIIIIOO OR 7C 



(THE WHITE SQUARES ARE LIGHTED 
DOTS ON THE MONITOR SCREEN) 



Fig. 3. Formation of a graphics mode character. 



• 80 characters in 24 lines in the character 
mode. High-resolution 256 by 248 bits in 
the graphics mode. 

• Custom-designed characters available in 
an 8 by 12 format. Seventh column blanked. 
User programmable in EPROM. 

• Compatible with 4 MHz processors. 
Memory-mapped video. Requires 8K static 
RAM. (2K for character mode only.) 

• Based on MC6845 Video-Display Genera- 
tor. Easily programmed to support any 
screen format. Interfaces to host processor 
via I/O ports. Produces video signal to a 
monitor or modified television. 

• Supported by high-level graphics subrou- 
tines to produce designs efficiently. 

• Software driver recognizes: 

—ASCII characters, upper and lowercase 
—Control characters: line feed, carriage re- 
turn, back space, bell 

—Cursor control codes (with scrolling capa- 
bility): cursor up, down, right, left and home 

• Light pen capability. 

Table 1. Summary of the characteristics of the 
Videographic board. 



64 Microcomputing, August 1981 




if He'd used select 
It wouldn't have taken seven days 

Learn SELECT in just 90 minutes. A whole new word processing software 
concept that kicks the coded key habit and frees you from complicated instruction 
manuals. SELECT is fast. SELECT is logical. With single key mnemonics, you'll use 
dozens of commands that instantly access the rich capabilities of this system. There's 
nothing like it. 

Simply hit "C" and you'll be ready to Create a document. 

Key "I" and you'll be in the Insert mode. 

Key "M" and Move entire blocks of text . . . and key dozens more. 

That's all there is to it. You'll get all that word processing software promises . . . plus a 
few surprises. 

SELECT with SUPERSPELL.* The only microcomputer software with an integrated 
spelling dictionary. To proof your text all you do, of course, is to key "S". SUPERSPELL 
with its 10,000 word dictionary scans your text at computer speed then displays and 
corrects all your typing errors. You can increase SUPERSPELL's word power and 
customize the dictionary by adding new words, one at a time. Ask to see it today at 
your local dealer. 



SELECT with SUPERSPELI just a little byte more. 



TM 




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Microcomputing, August 1981 65 





Photos 2 and 3. The front and back views of the Videographic display board and its shared static RAM memory. This dependable board, called the Econoram II 
from Godbout was the author's first and only RAM memory. Now it easily serves as the memory-mapped video. 



during the horizontal or vertical re- 
trace, but I have not included the 
software in my design. (The blanking 
signal is available at bit zero on the 
status input port.) 

A status flip-flop determines the 
current mode, character or graphic. 
This D-type flip-flop is accessed by a 



processor output command. The 
graphics mode will alter the circuit 
operation slightly: the dot clock fre- 
quency is divided by two, and the 
character generator EPROM is by- 
passed by a two-to-one multiplexer. 
After reprogramming the 6845 for a 
64-character by 124-line display 



(which happens in milliseconds), you 
have a high-density graphic display. 
As shown in Fig. 3, each dot on the 
screen matches to a bit in memory. A 
byte is split in a 4 x 2 matrix. The total 
screen density is a pleasing 256 dots 
across by 248 dots down, better than 
most ready-made microcomputers on 



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AP104 



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Apple II with Double Disk Drives 119 

Apple II, 9 inch Monitor & Double Drives ... 129 

Apple ///, two additional Drives & Silentype 139 

12 inch monitor plus accessories 99 

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TRS-80 Monitor or TV set 84 

TRS-80 Model III 129 

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5650 INDIAN MOUND CT COLUMBUS. OHIO 43213 (614) 868-9464 



Microcomputing, August 1981 



the market today. Photo 5 shows 
some sample designs. The software 
to create those dots is included later 
in this article, and can be used by 
both machine-language and higher- 
level programs. 



6845 Interface to the Processor 

As you already know, the charac- 
teristics of the video display are set 
by values stored in the 6845' s inter- 
nal registers by an initialization rou- 
tine run by your processor. Nineteen 
registers in the 6845 can be accessed 
by means of the S-100 data bus. These 
registers and their characteristics are 
shown in Table 2. 

Some of the registers are written 
only at system reset or character/ 
graphic mode changes to establish 
display format. Others are updated 
periodically as part of normal opera- 
tion (scrolling and cursor functions). 
Several fine discussions have ap- 
peared in Microcomputing and other 
magazines that explain the operation 
of the 6845 at length (see References). 

For your system to access the 6845' s 



TtiU is — WiraWHIC--- fi Television Display Interface 

Features: Full Cursor Control 

24 Lines of 9B Character* 
He»cry-»apped Uideo 
Proy utile Cursor Formats 
CustoM Characters 
Complete Software Routines 
G raphics — Density 256 x 248 



Character seV- 
f * a *H^JKlJW<^^ 1234567898 abcdefalMjM 

tr*tsor ()•♦,-./ : ; <->c\Jt_- 

S«*cta\ Characters: 

oa6eecatf*$tr** 000 



Photo 4. This picture, taken while in the character mode, shows a representative sample of the Video- 
graphic character set as programmed in the 2716 EPROM. You can change the shape of the characters as 
you desire, or create your own set. It was surprisingly easy— and fun— to invent the character set. 

internal registers, you need to gener- Write (R/W). Your circuit must create 
ate certain signals: Chip Select (CS), these signals within the 6845 mini- 
Enable, Register Select (RS) and Read/ mum timing specifications. I have 






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Microcomputing, August 1981 67 




( 



I I / 



\ \ \ \ 




Photo 5. These are simple geometric designs drawn by Videographic while in the graphics mode. They show the flexibility of this nearly 8K bytes (63,488 bits) 
display. Software in Listing 2 will plot or unplot dots, as well as draw straight lines between any two points you specify in a calling program. 



implemented a satisfactory interface 
with a 4 MHz bus operation as shown 
by the waveforms in Fig. 4. Note that 
the 6845 specifications are met. If 
your processor is slower than 4 MHz, 
you may be able to eliminate the wait 
states and the PRDY signal. 

Table 2 shows that the address reg- 
ister is a five-bit write-only register 
used as an indirect or pointer regis- 
ter. Its contents are the address of one 
of the other 18 registers on the chip. 



When RS is low, the address register 
itself is addressed. When RS is high, 
the register file pointed to be the ad- 
dress register is accessed. In other 
words, to write to any particular reg- 
ister file, two output cycles must oc- 
cur; one to point to that register file, 
and the other to read/write data in it. 
The RS line is connected to the sys- 
tem address line (the least signifi- 
cant bit), so the two output ports to 
change a register file will have con- 



6845 


Register 


Register File 


Program 


#of 


Read 


Write 


RS 


Number 


Name 


Unit 


Bits 


• 


• 





— 


Address Register 


— 


5 


No 


Yes 




RO 


Horizontal Total 


Char. 


8 


No 


Yes 




Rl 


Horizontal Displayed 


Char. 


8 


No 


Yes 




R2 


H. Sync Position 


Char. 


8 


No 


Yes 




R3 


H. Sync Width 


Char. 


4 


No 


Yes 




R4 


Vertical Total 


Row 


7 


No 


Yes 




R5 


V. Total Adjust 


Scan Ln. 


5 


No 


Yes 




R6 


V. Displayed 


Row 


7 


No 


Yes 




R7 


V. Sync Position 


Row 


7 


No 


Yes 




R8 


Interlace Mode 


— 


2 


No 


Yes 




R9 


Max Scan Length Address 


Scan Ln. 


5 


No 


Yes 




RIO 


Cursor Start 


Scan Ln. 


7** 


No 


Yes 




Rll 


Cursor End 


Scan Ln. 


5 


No 


Yes 


* i 


R12 


Start Address (H) 


— 


6 


No 


Yes 


* 1 


R13 


Start Address (L) 


— 


8 


No 


Yes 


* 1 


R14 


Cursor (H) 


— 


6 


Yes 


Yes 


♦ 1 


R15 


Cursor (L) 


— 


8 


Yes 


Yes 


* 1 


R16 


Light Pen (H) 


— 


6 


Yes 


No 


* i 


R17 


Light Pen (L) 


— 


8 


Yes 


No 


Table 2. 


TheMC6845 


internal register descriptions. 


The values marked by ar 


i asterisk 


may be up- 


dated du 


ring regular use. The position marked by two asterisks is explained < 


it length 


in the text. 



Input/Output IC40 Input 


Output 


Address pin Function 


Function 


60 (xx 1000x0) Yl Not Used 


Change to Graphic Mode 


61 (xx 1000x1) Y2 Video Board Status 


Change to Character Mode 


70 (xx 11 00x0) Y5 Not Used 


6845 Register Select 


7 1 (xx 1 1 OOx 1 ) Y6 6845 Register Read 


6845 Register Write 


Table 3. Input and output addresses are decoded by IC40, 


a 74LSI38. It is a 3 to 8 decoder. Video- 


graphic uses only its Yl, Y2, Y5 and Y6 outputs. The x's in 


the address are don 't-cares, and are as- 


sumed to be (01— -0-} in Videographic. 





secutive addresses. (In my design, 
I/O ports 70H and 71H.) The routines 
to initialize and maintain these regis- 
ters are part of the software listing 
presented here. 

I decoded two more addresses so 
that I could change the Videographic 
mode from character to graphics and 
back, as well as input the status of the 
light pen and blanking signals. All ad- 
dresses are detailed in Table 3. 

TV Monitor and Light Pen 

I used the popular Leedex Video 
100 as a monitor. It can be purchased 
from most mail-order outlets from 
$129 to $150. It is a good buy— it of- 
fers great bandwidth for the Video- 
graphic board and easy operation. If 
you intend to use an adapted TV re- 
ceiver, it must have about a 6 MHz 
bandwidth to work without signal 
loss. 

If you plan to use a TV with severe 
overscan, as most nonmonitor TV 
sets are designed to have, use a slight- 
ly faster clock rate. A 14 MHz clock 
will let you program the 6845 with 
the same page size, but give you more 
time for vertical and horizontal blank- 
ing so that you can correct for TV 
screen overscan. When changing the 
dot and character clock frequency, 
you will have to modify the register 
file data somewhat to account for the 
higher clock rate and maintain the 
same screen update timing. 

Implementing the light pen hard- 
ware is easy. The + 12 V I needed for 
the circuit came right from the power- 
on LED board in back of the monitor. 
The monitor offered a convenient 
spot to mount the components, and 
the front panel of the TV had two 
spots perfect for the miniature phone 
plug and sensitivity control. The sig- 
nal is sent to the video board where it 
is buffered and used by the 6845 and 
the S-100 bus. Photos 6a and 6b show 
my version of the light pen compo- 
nents. 



Microcomputing, August 1981 



T/Maker II: 

it not only does more than VisiCak, 

it does it on your computer. 



VisiCalc is a fine aid for the computation of numerical 
problems. But it does have two major limitations: it is 
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Works with words as well as numbers. Like VisiCalc, 
T/Maker II reduces the manual tasks involved in comput- 
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Projections 
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As an example of what T/Maker II can do, see the chart below. The operator entered only the data shown in boldface, 

T/Maker II calculated and reported all the other values. 





1978 


— Actual — 
1979 


Growth 
1980 Rate 


Average 


Total 
(OOO's) 




1981 


—Projected— 
1982 


1985 


Item A 


42,323 


51,891 


65,123 24.04 


53,112 


159.34 




80,782 


100,206 


191,262 


ItemB 


45,671 


46,128 


49,088 3.67 


46,962 


140.89 




50,891 


52,761 


58,791 


Total 


87,994 


98,019 


114,211 13.93 


100,075 


300.22 




131,673 


152,966 


250,053 


% Item 


48.10 


52.94 


57.02 8.88 


52.69 


158.1 




61.35 


65.51 


76.49 


% Item 


51.90 


47.06 


42.98 -9.00 


47.31 


141.9 




38.65 


34.49 


23.51 


Total 


100.00 


100.00 


100.00 - 


100.00 


300.0 




100.00 


100.00 


100.00 






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Microcomputing, August 1981 69 



You can construct your own light 
pen with an old pen cartridge and 
phototransistor. However, I elected 
to buy a light pen for $20 from 3-G 
Company, Inc., Dept. KB, Route 3 
Box 28A, Gaston, OR 97119. As it 
sees the electron beam when held 
close to the screen, the high signal at 
LPSTB on the 6845 will latch the cur- 
rent address of the character in file 




registers R16 and R17. The processor 
can then access these two registers to 
determine the location to which you 



are pointing the light pen. The neces- 
sary software, although not exactly 
trivial, is straightforward and will not 



Z-80 OUTPUT CYCLE 



Z-80 INPUT CYCLE 



♦ 2 















CYC 
T W 










.1 












-TYT I P" 








J 






• 


T| 




T 2 




LE — 


T W2 


T 3 


"1 




T| 




T 2 




T WI 




T W2 


T 3 































































































L 




DATA 
DO- D7 



6845 R/W 



6845 CS 




6845 ENABLE 



72 PRDY '. 



STABLE 



I 



-625nsec- 

(450) 



1 



/ 



\ 



l«— 375nsec »\+ 
I (160) |_ 



\ 



6845 

READS 

DATA 



mmx \ 



I 



Z80 Z80 

SAMPLE SAMPLE 



STABLE 



IX 




- 



\ 




— J 

:2 



y 



/ 



\ 



I 25"isec 
(I) 



J V 



\M\±J 



\ 



Z80 Z80 

SAMPLE SAMPLE 



( 16845 MINIMUM SPECIFICATIONS 



Photo 6a. The front panel of the Leedex Video 100 Fig, 4. The processor interface waveforms. The circuitry was designed to avoid exceeding any of the 6845 
modified for light pen use. timing specs. All specs are minimums and are shown in parentheses. 




Photo 6b. The transistor interface that I designed 
to support the light pen feature fits easily on a small 
breadboard layout. One night's construction was 
all that was necessary to assemble it and mount it 
as you see in this picture. The +12VI needed for 
the circuit was conveniently available from the 
power-on LED board nearby. 



NAME 



SYSTEM RESET 



SIG-A 



WAVEFORMS 
_l L_ 



SIG-B 



SIG-C 2Z^ 



J — I I — I I I I I I L 



SIG-D 
SIG-E 
SIG-F 
SIG-G 



7 



mi 



-L_r~i_r~L_r~i_n 



777\ 



J 



1 



'////\ CHARACTER CLOCK \ 



SHIFT/LOAO ///A 



38 -ML SI66 
LOAD'S 
NEW CHAR 



34 74LS273 
LATCHES NEW CHAR 

. 37- 6845 PUTS OUT 
NEW ADDRESS 



1 r 



CHARACTER 
MODE 




CHAR SERIAL OUT 



CHAR OUT ■ 4 BH 



v /////, '/////. v//////////////a □ rr m a ® m \ a rmnfTi HMmv J 

~l_j lj 1 r 



GRAPHIC'' DOT CLOCK 

._r~L_j l_t 



GRAPHIC / 
M0DE\ 



DELAY LATCH 



GRAPHIC SERIAL OUT 



GRAPHIC OUT '4H 



\ a 1 a 1 e a_r0 a 



^ DELAY DATA 

CLOCKED 



U" 



u 



Fig. 5. These are the waveforms associated with the creation of a video character. SIG-A is derived so that 
the dot clock timing will have proper phase relationship to the SHIFT/LOAD signal when a reset pulse 
occurs. 



70 Microcomputing, August 1981 



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Microcomputing, August 1981 71 



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be discussed further. 

The Two-Character Delay 

The sequence of character opera- 
tions is as follows: 

The 6845 presents a character ad- 
dress for the screen update to the 
memory. The memory after a set-up 
delay presents the character to the 
latch, IC34. The character in IC34 is 
then presented to the character gen- 
erator, IC37, or to the graphics multi- 
plexer, IC33, depending on the mode 
selection. The dots for the specified 
scan row of the character are then 
presented to the shift register, IC38, 



and shifted out at the dot clock rate to 
produce the video signal. Fig. 5 
shows the timing of this sequence for 
the character and the graphic modes. 
Because of the set-up time delays in 
the memory, two characters are actu- 
ally being processed at any one time- 
one character being accessed from 
the shared memory, and one charac- 
ter being output by the character gen- 
erator or graphic multiplexer to the 
shift register. (Actually, the second 
character is one row of dots, not the 
whole character.) Thus, the two 6845 
signals, cursor and display enable, 
must be delayed two character inter- 



ADDR 
SELECT 
DIP 
SWITCHES 










> 














1. 






* 




> 


1 




74 











E> 



74LS32 



-> AENAB 




ADDR 
SELECT 
DIP 
SWITCHES 
















*T 




= 




L 




' 7 















E> 



74LS32 



jj IC5 

741 



IC3 



Ll!/^^rc7yi-^> 8 t > BRDSEL 

LSOO *5V I 1 ' ^Y 

\ | ICII <7 



^ 



-> BENAB 



* 1C PIN BENT UP 
TO DISCONNECT 



GROUND 



ADDR BUS 

INVERTING 

BUFFER 



ADDR BUS 

NON-INVERTING 

BUFFER 



ICIO 






ICII 




8ILS96 




8ILS95 




1 


19 






I 


19 


/ 


k 













RAM 

INTERNAL 
DATA OUT \ 
BUS 



-> 



BRDSEL 



MEMWR|fc8 




A R/W 



>B R/W 



SELECT 
IK ROW 
SIGNALS 



BRDSEL 



♦ 5V 



PSYNC [76> 



02 Ql>-e- 



PRDY <72> 




FOIL TRACES 
CUT 



> 



ENABLE 
IK ROW 
SIGNALS 



INTERNAL 

ADDR 

BUS 



RIBBON 
CABLE TO 
VIDEOGRAPHIC 



BDSEL 
BDSEL 



GROUND 



DOO 
DOI 
002 
DO 3 
D04 
D05 
DO 6 
D07 



AROWO 

AROWI 

AROW2 

AROW3 

AR0W4 

AROW5 

AR0W6 

AROW7 



RO 

Rl 

R2 

R3 

R4 

R5 

R6 

R7 



ADDRESS 
MAO TO MA5 
MA6 TO MA9 



Fig. 6. The simple changes made to the 8K static RAM board. The intercepted signals were routed to the 
Videographic board over the ribbon cable. 



72 Microcomputing, August 1981 



vals by IC44 to accommodate this de- 
lay effect. 

Cursor Generation 

The cursor signal is true whenever 
the 6845 output address matches the 
internal value in the cursor address 
register pair (R14 and R15). This sig- 
nal is processed in such a way with 
bit 7 of the incoming character byte 
(the bit that determines the black-on- 



white status of the video) so that the 
6845 cursor signal will always cause a 
reversal of the character. 

The cursor can be programmed to 
underline, reverse the entire charac- 
ter, slow blink, fast blink or stay on 
steady. Registers R10 and Rll con- 
trol the format of the cursor, and R14 
and R15 control its position. The low- 
order five bits of R10 (bits through 
4) specify the scan row on which the 



RIBBON CABLE 



SO 



AROWO 



A ROW I 
AROW2 



AR0W3 



BROWO 



BROW I 



BROW 2 



BROW 3 



Rl 



15 



a 



R2 



40 

4 



14 

7 



R3 



13 



R4 



38 

12 



IY 



2Y 3Y 

IC30 
74LSI57 



4Y 



STB SEL 

'A IB 2A 2B 3A 3B 4A 4B 



33 



3 I 



26_ 



RIBBON 

CABLE 

TO 

MEMORY 

BOARD 



ii 



10 



14 



13 



15 
r—0 STB 

^ L_!A 



R5 



37 

4 



R6 



R7 



36 
9 



BDSEL 



35 
12 



IY 



2Y 3Y 

IC3I 
74LSI57 



4Y 



A IB 2A 2B 3A 3 



"LTllS 



k 



14 



13 



12 



ll 



SEL 
4A 4B 



10 



10 



14 



13 



B 6845 

~1a 1 MEM 



29 



BDSEL 



a — a — £ £ & 6 6 



YO Yl Y2 Y3 Y4 Y5 Y6 Y7 

IC54 

74LSI38 G | 

G2A G2B C B A 



JJ 



MEM 
DO 7 

D06 

DOS 
DO 4 

D03 
D02 
DOI 
DOO 



♦ 5V 



♦ 5V 
J 



i 



_TL 



14 



44 



18 



43 



17 



42 



16 



14 



41 



17 



15 



18 



1 



IC34 
74LS273 



CL 

"77 



12 



15 



16 



i9 



SHIFT/LOAD>- 




-12 



13 



15 



IA 
2A 
3A 
4A 

IB 
2B 
3B 
4B 

STB 



IC33 
74LSI57 



IY 
2Y 
3Y 
4Y 



SEL 



LO 



HI 



6845 

MAIO 
MAI I 
MA I 2 



-> MEM D07 



12 



I IC 52 
[8ILS98 



18 16 14 12 

._ 917 Bis Bi3 fin 



-<GRAPHICS 



19 



22 



23 



35 36 37 38 



AIO 
A9 
A8 
A7 

A6 

A5 
A4 
A3 
A2 
Al 
AO 



IC37 
2716 



DO 
01 
D2 
D3 
D4 
05 
D6 
D7 



CS 



PD/PGM 



20 



10 



13 



15 



16 



17 



->CDO 
->CDI 
->CD2 
->CD3 
->CD4 
->CD5 



->CD6 



->CD7 



18 



POWER DOWN 



OPS 



-> GRAPHICS 



RA3 RA2 RAI RAO 

IC39 
6845 



Fig. 7. The complete schematic for Videographic. 




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cursor is to start; the Rl 1 specifies the 
scan row on which the cursor is to 
end. If R10 bits through 4 are all 
equal to 0, and Rll is 11, the cursor 
will occupy lines through 12, or the 
entire character. The character is re- 
versed. If the value of 10 is stored in 
R10 bits through 4, the cursor be- 
comes a two-line underscore. This is 
what I prefer. 

Bits 5 and 6 of R10 determine cur- 
sor blinking. If bit 5 is on and bit 6 is 
off, the cursor is not displayed at all. 
You can use this to blank the cursor 
for graphic display or other uses. If 
bit 6 is on, the cursor will blink. If bit 
5 is off, the blink rate is about four 



times a second. If bit 5 is on, the blinl 
rate is two times per second. 

The Memory Board 

Fortunately, all the devices I needj 
ed to make Godbout's 8K Static Econ 
oram II share memory with the Vid| 
eographic could come on unuse< 
components right from the board] 
Fig. 6 shows the components 
changed to interrupt the data and ad| 
dres s signal s, and produce the BDSEj 
and BDSEL for the video board to us< 
Since the 21L02 chips are arranged ii 
IK rows, the Godbout board decode) 
the addresses into eight row-enabh 
signals. I cut those traces and route< 



S'OO 17c 36 

BOAR0 

2 



j 74LS24I 



AO | 79 \ 
PRESET | 75 \ 




013 |"42~} 

012 [ 41 | • 

Oil [~9T> 

DIO | 95 I — • 



Fig. 7b. 



74 Microcomputing, August 1981 



those signals over the ribbon cable to 
IC30andIC31. 

These chips also get eight decoded 
row-enable signals from the 6845 ad- 
dress lines MA11, MA12 and MA13. 
Normally, 6845 row-enable signals 
get through until the Econoram is ac- 
cessed by the processor. At that time, 
BDSEL goes low, and the Econoram 
row-enable signals are routed through 
IC30 and IC31 back through the rib- 
bon cable to the memory chip-enable 
lines on the proper row. 

To get the memory output, I merely 
tapped the data-out bus on the Econo- 
ram, and routed it over the ribbon ca- 



ble to IC34, the eight-bit latch. 

If you desire to use 2114 static 
RAMs on the Videographic board, 
you will have the advantage of lower 
power requirements and fewer mem- 
ory chips, 16 instead of 64. (You also 
have the option to wire up only 2K as 
memory, but be aware that you will 
then have no graphics capability. 
However, a whole video display of 
characters with the minimum of two 
2114s will be available to you. At $6 
apiece, low memory costs.) 

Construction 

Fig. 7 provides the complete sche- 




Dl SP 

LNAB 



VERT SYNC 
HORIZ SYNC 



matics for Videographic. As I noted 
in the block diagram, the 6845 is the 
central chip of the circuit. Photo 7 
shows my prototype, and there is 
enough room left over for on-board 
memory, or expansion to a keyboard 
input interface. I used the excellent 
8804 breadboard from Vector Elec- 
tronics Company (12460 Gladstone 
Ave., Sylmar, CA 91342). The chips 
are labeled starting at IC30, merely 
because other hobby boards in my 
computer have already used the first 
29 labels. 

Wire-wrapping is the only means 
for a hobbyist to connect this system 
together. I used the Just Wrap tool 
(from OK Machine and Tool Corp., 
3455 Conner St., Bronx, NY 10475) 
for point-to-point wire- wrapping; it is 
far superior to other alternatives 
when wire-wrapping on a large scale. 
Watch out though— no matter how 
much experience you've had, a small 
percentage of wrappings will ajways 
turn out bad. So double-checking 
with a circuit tester after wrapping is 
an absolute necessity. 

Photo 8 shows the reverse side of 
the Videographic board. Note that 
the wires appear neat and taut. 

This brings us to the actual con- 
struction. There is plenty of good ad- 
vice in the magazines these days on 
how to construct an electronic proj- 
ect. (Don Lancaster's TTL Cookbook 
has a good set of tips.) I want to pass 
along some heartfelt rules that I have 



l__! v __J 



Fig. 7c. 



IC 


Type 


Pin 


30 


74LS157 


16 


31 


74LS157 


16 


33 


74LS157 


16 


34 


74LS273 


20 


35 


74S04 


14 


36 


74LS241 


20 


37 


2516 EPROM 


24 


38 


74LS166 


16 


39 


6845 


40 


40 


74LS138 


16 


41 


74LS74 


14 


42 


74LS74 


14 


43 


74LS93 


14 


44 


74LS175 


16 


45 


81LS97 


20 


46 


74LS125 


14 


47 


74LS74 


14 


48 


74S86 


14 


50 


47S11 


14 


51 


74S05 


14 


52 


81LS98 


20 


53 


81LS97 


20 


54 


74LS138 


16 


55 


74LS09 


14 


56 


74LS00 
Fig. 7d. IC listing. 


14 



Microcomputing, August 1981 75 




Photo 7. The complete Videographic video board is shown in this close-up 
component view. Note that there are plenty of despiking capacitors, and 
that there is enough room left on this prototype for onboard static memory if 
desired. The numbers on the chips correspond to the IC numbers used 
throughout this article. 




Photo 8. The bottom, or wire-wrapped, side of the video terminal board. 
Neatness counts, and saves you hours of troubleshooting later. The video 
cable plugs into a socket that is exposed to the board. All high-frequency 
wire runs are kept as short as possible. 



learned the hard way. 

• Capacitors, capacitors, capacitors! 
Use plenty of them. I try to get almost 
one .1 uF disk capacitor per TTL 
chip. Keep the leads as short as possi- 
ble. Put a 10 uF tantalum at the out- 
put of the regulator, and a 1 uF tanta- 
lum at the end of each chip row. 
Watch those polarities! This practice 
is especially important at the clock 
speeds in Videographic. 

• It is impossible to avoid errors in 
wire-wrapping, so Xerox a copy of 
your schematic. Make the connec- 
tion. Test it. Then mark it off with a 
colored pencil on the schematic. 
Sound easy? It is, if you want to avoid 
hours of headaches later. You'll be 
surprised at the number of connec- 
tions you will do over. When the 
board is complete, test each line 
again and mark it off on the schemat- 
ic. It saves hours. 



Vss 



REFRESH . 

MEMORY < 

ADDRESSES ' 



RESET 
LPSTB 
( MAO 
MA I 
MA2 
MA3 
MA4 
MA5 
MA6 



MC6845 
CRTC 



10 



MA7 •+- 

MA8 -*- 

MA9 -*- 

MAIO ♦■ 

MAI I • 

MAI2 ■*- 

MAI3 ♦ 



DISPLAY ENABLE 

CURSOR 

V C C 



20 



• Use epoxy to cement the sockets to 
the board. Keep the fastest chips close 
together, and the 12 to 14 MHz wire 
runs as short as possible. Line up all 
the chips in one direction so that the 1 
pins are always in the same corner. 
Make no exceptions. 

•Wire all ground wires first, then all 
+ 5V supply lines. Use many colors 
of wire to help later troubleshooting 
or modifications. 

• Don't have wires too loose. Keep 
them close to the board, thereby close 
to the ground plane. Do all soldering 
before starting to wire-wrap. 

• Power up the board before plug- 
ging in any chips to check the supply 
regulator performance. It makes sense 
to smoke-test the regulator first so 
one doesn't risk all the IC chips. 
•This is the last bit of advice, and it 
is the hardest to live by. Document 
whatever wiring changes you make 



40 



39 



38 



VSYNC 
HSYNC 
RAO^ 



37 



36 



35 



34 



-*■ RAI 
-» RA2 
-*. RA3 

-+■ RA4 



ROW ADDRESSES 
> FOR CHARACTER 
GENERATORS 



33 
32 



31 

4 — 

30 

♦— 

29 



28 



27 

-• — 
26 



25 



24 



23 

<• — 



■*• DO 
-•> Dl 
■♦ D2 
-»• D3 
-»• D4 
-»• D5 
-•» D6 
-»• D7 

— CS 

RS 

— E 



N 



) DATA BUS 



v PROCESSOR 
/ INTERFACE 



} CONTROL 



22 



21 



R/W 



CLK 



Fig. 8. The Motorola MC6845 pin-out. A prospective user of this chip should obtain a copy of its technical 
specs. See the article for details. 

76 Microcomputing, August 1981 



on your schematic. Do not ever leave 
your project for the day without writ- 
ing your changes down neatly. 

If you have been meticulous, Vid- 
eographic will start to work the first 
time you plug it in. (Remember, the 
6845 will have to be programmed be- 
fore it operates the way you want it 
to.) 

Troubleshooting a system without 
good tools is almost impossible. Al- 
though a limited test circuit is built in 
(the actual display), you may have to 
use an oscilloscope to test further. 
Logic testers will help you to hunt 
down small problems. Use the wave- 
forms in Fig. 5 to track the signals 
from the crystal oscillator to the vari- 
ous clocks. If those check out, verify 
proper operation of the memory 
(write and read to it), and the inter- 
face to the 6845 (run little software 
output loops while checking 6845 
control signals). Kick yourself if you 
find that the bug turns out to be a 
wire-wrap error. You were warned. 
Photo 9 shows some of the growing 
pains while Videographic was being 
debugged. 

Software Driver 

Table 4 lists the available control 
codes to operate the driver. The Vid- 
eographic software driver is con- 
tained in Listing 2. I have used my 
own assembler to create the listing, 
but most of the conventions found in 
commercial assemblers are present. 
The program is written in Z-80 object 
code starting at 1030 hex. It has four 
sections: 

1. Routines for character loading 
and cursor control. 

2. Subroutines for section 1 and 




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Photo 9. Troubleshooting a new circuit can be half the fun of construction. Here, the video logic is going 
through some growing pains. 



outside program use. 

3. Initialization routines for the 
character and graphics modes. 



4. Routines for drawing and un- 
drawing dots in the graphics mode. 
An algorithm to draw lines between 



any two points on the screen is in- 
cluded to speed up the larger routines 
to improve overall speed. 

A buffer area of 15 bytes must be 
set aside for the Videographic in a 
memory area. (I use BFFO to BFFF.) I 
designed the software so only two 
bytes need to be altered to relocate 
this buffer area. That is why I make 
such extensive use of the IX register 
throughout the subroutines. 

Actual memory displayed in the 
character mode is 80x24 characters, 
or 1920 bytes. The starting point in 
the 8K RAM could be anywhere, de- 
pending on the contents of the 6845 
register files R12 and R13. Changing 
these two registers will scroll the 
screen for the user. 

When in the 256x248 graphics 
mode, memory displayed is much 
more— 64 times 124, or 7936 bytes. 
That is 63,488 bits of memory used, 
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R12 and R13 register files will stay at 
zero at all times in the graphics mode. 

Scrolling 

Scrolling is the management of a 
video display. The 6845 can scroll by 




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78 Microcomputing, August 1981 



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Microcomputing, August 1981 79 



character, line or by page simply by memory address. The software pre- 
starting its update cycle on a different sented here scrolls line by line. The 





ASCII Code 


Name 


Function 




07 


Cntl-G 


Rings the terminal bell. 




08 


Cntl-H 


Backspace. (Cursor Left) 




09 


Cntl-I 


Cursor up. 




OA 


Cntl-J 


Line feed. (Cursor Down) 




OB 


Cntl-K 


Cursor forward. 




OC 


Cntl-L 


Cursor home (upper left corner). 




OD 


Cntl-M 


Carriage return. 






Table 4. Software driver commands. 



Register Function 

of Register 

RO horizontal total 

Rl horizontal columns displayed 

R2 horizontal sync position 

R3 horizontal sync width 

R4 vertical total 

R5 vertical total adjustment 

R6 vertical rows displayed 

R7 vertical sync position 

R8 interlace mode 

R9 maximum scan line 

RIO cursor start 

Rll cursor end 
R12 

through cursor and RAM start 
R17 



hara 


cters 


Graphics 


80 x 


24 


256 x 248 


102 


[66) 


102 (66) 


80 


[50) 


64 (40) 


86 


(56) 


78 (4E) 


12 | 


0C) 


9 (09) 


24 


(18) 


127 (7F) 


19 


(13) 


25 (19) 


24 


(18) 


127 (7F) 


24 


(18) 


125 (7D) 





(0) 


(0) 


11 


[0B) 


1 (01) 


73 


(49) 


(0) 


11 


[0B) 


(0) 



(0) 



(0) 



Table 5. Appropriate MC6845 values to be stored in the internal registers for the character and 
graphics display formats. The values given are for a 12.440 MHz crystal dot clock. The decimal value 
is given, followed by the hexadecimal equivalent in parentheses. If you need a faster clock, some of 
these registers have to have different values. (For example: 14. 138 MHz crystal, R0 must be set to 70 
hex, R2 must be set to 5A hex character mode and 52 hex for graphics mode.) 



Listing 2. The Videographic software driver. (Listing continues on page 163.) 



0000 
0000 
0000 
0000 
0000 
0000 
0000 
0000 
0000 
0000 
0000 
0000 
0000 
0000 
0000 
0000 
0000 
0000 
0000 
0000 
0000 
0000 
0000 
0000 
0000 
0000 
0000 
0000 
0000 
0000 
0000 



1 

100 
110 
120 
130 
140 
150 
160 
170 
180 
190 
200 
210 
220 
230 
235 
240 
250 
260 
270 
280 
290 
300 
305 
310 
320 
330 
340 
350 
360 
370 



ORIG 
********************************************* 

*** VIDEOGRAPHIC DRIVER SOFTWARE *********** 
********************************************* 

*** WRITTEN BY J.J. MARTINKA **************** 
*** OCTOBER, 1980 **************** 

********************************************* 



THIS DRIVER FACILITATES THE USE OF THE VIDEO- 
GRAPHIC BOARD AS A CONSOLE DISPLAY DEVICE. 
IT IS PRESENTED AS FOUR SECTIONS: 

1) THE ROUTINES CALLED FOR CHARACTER LOADING 
AND CURSOR CONTROL 

2) SUB-ROUTINES USED BY SECTION 1) AND ARE 
ACCESSIBLE FOR OUTSIDE PROGRAM USE BY 
TEXT EDITORS OR OTHER PROGRAMS 

3) THE INITIALIZATION ROUTINE NEEDED PRIOR TO 
6345 VIDEO CHIP OPERATIONS 

4) SHORT GRAPHICS ROUTINES 

NOTE: THIS PRESENTATION IS ASSEMBLED BY A HOME 
BREW ASSEMBLER, AND ITS OUTPUT IS FREE FORMAT. 
THE ONLY REAL DIFFERENCES FROM COMMERCIAL 
ASSEMBLERS ARE: 

-LABELS ARE ASSIGNED WITH THE COLON IN FRONT 
INSTEAD OF BEHIND. I.E. 20 :ECHO NOP 
-JP, JR, AND CALL INSTRUCTIONS THAT HAVE 
CONDITIONS ARE PRECEEDED BY A PERIOD. 
I.E. CALL .NZ, ADDRESS JR .C, ADDRESS 




principle is simply that new data is 
entered on the bottom line of the dis- 
play. When the bottom line is full, the 
entire display is moved up one line. 
In the process, the top line, contain- 
ing the oldest data, is scrolled off the 
screen. The display can be scrolled 
down as well as up, and the TV screen 
acts as a movable window. The driv- 
er program changes the update start 
address of the 6845 in increments of 
80 (for the 80-character line width). 

When the scrolling process com- 
pletes several video pages and comes 
to the end of the memory-mapped 
8K, a wrap-around occurs— the ad- 
dress 8192 is equivalent (at least from 
the point of view of the 6845) to the 
address 0. Thus, the wrap-around oc- 
curs automatically, even if it occurs 
in the middle of the screen. 

Note, however, that the 6845 can 
address up to a full 16K of memory. I 
use only 13 bits of the 14-bit address. 
I leave the most significant bit of the 
6845 address disconnected. But the 
cursor address register, light pen ad- 
dress register and the update address 
register are 14-bit registers. All 14 
bits must match a displayed video 
character to expect proper operation. 
This fact, when overlooked, can cause 
problems when you are writing your 
own driver routines. Be especially 
wary when wrap-arounds occur in 
the middle of a page. 

Conclusion 

I hope Videographic will interest 
you as much as it did me. It is a com- 
plete video system, and will keep you 
busy for months with its many possi- 
bilities. ■ 

References 

1. Motorola Advance Information 
Notes AD 1-465, "MC6845 CRT Con- 
troller (CRTC)," Motorola Semicon- 
ductors, 3501 Ed Bluestein Blvd., 
Austin, TX 78721. 

2. Hass, Bob, "Single Chip Video 
Controller," Byte, May 1979. 

3. Beetem, John, "Vector Graphics 
for Raster Displays," Byte, October 
1980. 

4. Lancaster, D., TV Typewriter 
Cookbook, Indianapolis, IN: Howard 
W. Sams & Co., 1976. 

5. Wierenga, Theron, "Construc- 
tion of a Fourth-Generation Video 
Terminal," Byte, August 1980. 

6. Knutson, Jeff, "A Video Graph- 
ics Primer,' Microcomputing, No- 
vember 1980. 



80 Microcomputing, August 1981 



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Microcomputing, August 1981 



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Microcomputing, August 1981 83 



G 



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A 



w 



The Shiny Apple 



By Harold Nelson 
Microcomputing Technical Editor 



In the five years since two young men 
started building m.crccomputers in a ga- 
rage in California, Apple Computer, Inc., 
has become, according to The Wall Street 
Journal, "one of the hottest high-technolo- 
gy companies to go public." Among com- 
puterists, it is also one of the microcomput- 
er industry's most respected manufactur- 
ers. The Apple II itself is one of the chief rea- 
sons why— it's a sound computer, easily 
adapted to virtually any purpose. Also, Ap- 
ple encourages independent producers to 
develop products for use with its comput- 
ers, a philosophy that lets users easily mod- 
ify their Apples when they need to. 

Apple! est '81 

In spite of early difficulties with the new 
Apple III computer, consumer interest in, 
and enthusiasm for, Apple seems to be un- 
diminished. June's highly successful Ap- 
plefest '81 show (10,000 paid attendance), 
sponsored by the Apple/Boston group of 
the Boston Computer Society, underlined 
this point. Even though the temperature 
was close to 90 degrees, with the humidity 



not far behind, both spirits and exhibitor 
sales were high. The show was not only 
well-supported by current and potential Ap- 
ple owners; Apple Computer itself was well- 
represented. They provided a public hands- 
on room with about 20 Apple Ms, and offered 
free 45-minute "lessons" on 15 Apple Ills. It 
wasn't easy to find a computer in either of 
these rooms that was not being used. 

Apple III, Round 2 

The Apple announced its Apple III well 
over a year ago (May 1980, to be specific). 
Orders were enthusiastically placed and re- 
ceived. Then the long wait began. 

Prior to March of this year, only some 
1000 Apple Ills were delivered— many 
months behind the first scheduled delivery 
dates. The machines only became readily 
available this spring. 

Soon after the first Apple Ills were out, 
horror stories began to appear. These ranged 
from reports of minor problems to state- 
ments that the machine was a total failure 
and that Apple would not be able to repro- 
duce its success with the Apple II. Rumors 



began to circulate that the company itself 
was in trouble. 

The Apple III had some very real prob- 
lems, but it now appears that the doomsay- 
ers were a little hasty. Obviously, Apple re- 
leased the Apple III prematurely. Phil 
Roybal, Apple's Product Marketing Manag- 
er, does not shy away from discussing 
these problems, which included: 

• Intermittent difficulties with program- 
mable random-access memory. Apple dis- 
covered that corrosion formed on memory 
board contacts after the computers were 
shipped. Coating these contacts with a pro- 
tective lubricant at the factory has eliminat- 
ed the problem. 

• In shipment, ICs worked out of their sock- 
ets, a result of movement of the large moth- 
erboard and loose sockets. The solution 
was to use tighter sockets with a metal tab 
to hold the ICs in place. 

• The tighter sockets did not seem to rem- 
edy the above problem. Actually, the new 
sockets caused new problems with similar 
symptoms to those caused by the loose 
sockets. The new sockets were so tight that 




The Apple III features an 80-character, upper and lowercase dis- 
play, up to 128K of memory, one built-in disk drive and the capacity 
for more. (Computer courtesy of Computer Town of Salem, NH) 




Applefest '81 in Boston was hot, humid, crowded and a huge 
success. 



84 Microcomputing, August 1981 



pins were ouen Deni wnen me ius were in- 
stalled. Apple didn't detect this at first, 
since the tabs tended to cover up the prob- 
lem during factory testing. The final solu- 
tion was to use the tighter sockets without 
the tabs. Now bent pins can be detected 
during factory inspection. 
• The very fine-line PC board first used in 
the Apple III made it hard to detect slight 
solder bridges occurring during assembly. 
Apple has lessened this problem by using 
wider traces on the PC board and by improv- 
ing quality-control measures. 

Roybal also said that, since these correc- 
tions, "the backlog of orders has been filled 
and production is up to par." Dealers and 
users we contacted are now pleased with 
the Apple Ill's performance. 

The only negative remark concerns the 
lack of software for the Apple III. Word 
Painter, Apple's word processor for the Ap- 
ple III, is not on the market, even though it 
was promised months ago; this fact has 
frustrated several Apple III purchasers. The 
delay, says Apple, is because Word Painter 
was written in Pascal, and the Apple III ver- 
sion of UCSD Pascal is only now being read- 
ied for release. 

Apple III Software 

Two new Apple III word processors, avail- 
able from independent producers, should 
therefore be welcomed by users, dealers 
and Apple itself. Rainbow Computing, Inc., 
(19517 Business Center Drive, Northridge, 
CA 91324) has released Write-On III (for a re- 
view of the Apple II versions of Write-On, 
see the June 1981 Byte, p. 186). Also, Type- 
Righter has been announced by Imagineer- 
ing, Inc. (c/o Adcast Advertising, 405 S. Far- 
well, Suite #10, Eau Claire, Wl 54701). If 
these word processors are any indication, 
the Apple III software vacuum should soon 
be filled. 

Some Apple III purchasers have also had 
trouble using its Apple II emulation mode. 
In this mode, the Apple III will run software 
written for the Apple II. Problems with this 
mode are, for the most part, l/O-related. For 
example, an Apple II program written for 
printer output with a printer interface card 
in slot 2 will not run on the Apple III. The rea- 
son is simple. The Apple III has a built-in 
printer interface that is addressable as slot 
7. If the Apple II software is designed to look 
for the printer in slot 2, it won't work. But the 
solution is also simple. Modify the Apple II 
software to send printer output to slot 7. 
Most emulation mode problems can be sim- 
ilarly solved. 

Apple knows it has made mistakes with 
the Apple III, but believes that they are now 
corrected. Apple's chairman and cofounder 
Steve Jobs expressed unqualified confi- 
dence while at Applefest '81 that the Apple 
III is finally on-line. 

But beyond discussing software being 
developed for the Apple III, both Jobs and 
Roybal are close-mouthed about future Ap- 
ple products. The message is that they 
won't disclose anything about new prod- 
ucts until they're certain that those prod- 
ucts are ready.! 



Apples Grow Well in Dallas 



By Tom Lukers 




Independent consultant Philip Russell is shown here training office staff on the fine 
points of VisiCalc on an Apple III. 



Apple is getting good reviews from 
dealers in the Dallas area, where 
Apple recently opened a new manufac- 
turing plant. 

Retailers and consultants are report- 
ing steady sales and satisfied custom- 
ers, and are happy with Apple's factory 
support and promotional efforts. 

"It wasn't long before we saw that al- 
most all of our income was from Apple 
sales," says one dealer. Another adds 
that Apple constitutes about 80 percent 
of his sales. 

Many customers are from large com- 
panies with corporate headquarters in 
Dallas. They like Apples because they 
work well either as stand-alone systems 
or as terminals in a corporate network. 
Some executives use them at the office, 
others use them at home and some do 
both. 

The Apple's friendliness is the key to 
its success so far, dealers say. 

"Most people want a buttoned-down 
system," says one retailer. "They want 
to be able to walk up to it and use it. Let's 
face it: most people aren't programmers 
or hardware hobbyists. They don't care 
about this bus, that bus or any bus. They 
just want to use the computer." 

The same dealer says that the Os- 
borne I, despite its price and features, 
won't have a great impact on Apple 
sales. 

"The Osborne I isn't a friendly 
system," he says. "Besides, the guy who 
buys an Osborne I probably wouldn't 
have bought an Apple, anyway." 

Pam Inserra, vice president of the KA 
Computer Store, says that several re- 



cent Apple promotional campaigns have 
given sales a shot in the arm. 

For example, a recent Apple road 
show for dealers and the general public 
was extremely successful, she says, and 
was followed by an increase in sales. 
And the advertising campaign featuring 
Dick Cavett also helped the store. 

"For a while, it was a regular occur- 
rence for someone to walk through the 
door, saying, 'Dick Cavett sent me,' " 
she says. 

People are not without their reserva- 
tions. Independent consultant Philip 
Russell, for example, is critical of the 
lack of software support for the Apple III. 

"As far as I'm concerned, the Apple II 
emulation mode is almost a failure, be- 
cause of its inflexibility," he says. "I 
have even considered recommending to 
one of my clients that he go back to the 
Apple II because of this." 

Compushop District Manager Richard 
Hartman warns that Apple could face 
some stiff competition if it isn't careful. 

"Apple is by far our leading seller," he 
says. "But some really serious competi- 
tion is looming on the horizon and Apple 
should be preparing for it. Atari sales are 
increasing every day. And Atari has the 
financial backing to give everyone a run 
for it." ■ 



Dr. Tom Lukers (PO Box 1949, 3625 Hen- 
drick Drive, Piano, TX 75054, Micronet 
70130,371) wrote the January 1981 cover 
story, "Assemble a Super Business 
System." 



Microcomputing, August 1981 85 



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You'd better not lie to your Apple when this program's running. 



To Tell the Truth 



By David B. Curtis 



Can a computer replace Scotland 
Yard? How much stress do you 
feel when another Klingon enters 
your sector? Who ate the last piece of 
leftover mince pie? Who knows the 
answers to these questions? 

The Apple II does, with the aid of 
this inexpensive and criminally sim- 
ple way to connect it to a psychogal- 
vanometer, or lie detector. 

The skin surface of the human 
body carries small electrical currents, 
and has a measurable resistance. This 
resistance is lowered by tension, 
physical exertion and other factors, 
which may be the result of lying or 
another form of stress. Psychogalva- 
nometers measure this varying resis- 
tance. 

Radio Shack sells a lie detector unit 
(catalog number 28-182) for $11.95. It 
includes two sensors that attach to 
two fingers of the subject's hand. The 
relative skin resistance tunes the fre- 
quency of an audio oscillator, which 
drives a speaker. When the subject's 
resistance goes down, the pitch of the 
generated tone goes up proportional- 

Because of the audio output, the 
Radio Shack lie detector is simple to 
interface to the Apple II. You connect 
the output of the oscillator to the cas- 
sette input of the Apple II, and use a 
small machine-language program to 
measure the frequency of the audio 
output of the lie detector. 

Construction 

Assemble the Radio Shack lie de- 
tector kit according to the instruc- 
tions that come with it. The kit is very 

Address correspondence to David B. Curtis, Route 
1, Cresco, I A 52136. 



simple; anyone who knows which have no trouble assembling it in less 
end of a soldering iron to hold should than an hour. Before proceeding to 













Listing 1. 










1000 


* :¥ :■»•: ■¥■¥■¥ ****** :* :*:* * :* :*:*:**:* :+e :*:* :+t :* * :* :*:*:*:* :* 








1010 


* 




* 








1028 


* 


LIE DETECTOR INTERFACE 


+ 








1030 


* 




* 








104© 


* 


DATE THIS REVISION : ll-OCT-SG 


* 








1050 


¥ 




* 








1060 


■¥ 


ENTRV - 


¥ 








1070 


■¥ 


CALLED FROM APPLESOFT AS USR 


¥ 








10S0 


¥ 


FUNCTION 


■¥ 








1090 


* 




■¥ 








1100 


* 


INPUT - NONE 


¥ 








1110 


■¥ 




¥ 








1120 


¥ 


OUTPUT - 


■¥ 








1130 


■¥ 


RETURN UALUE FROM 0-255 


■¥ 








1140 


■¥ 


REPRESENTING RELATIUE 


■¥ 








1150 


* 


SKIN RESISTANCE 


¥ 








1160 


* 




• 








1170 


* 




* 








1130 


* 


TO USE - 


• 








1190 


* 


APPLESOFT PROGRAM SHOULD 


* 








1200 


* 


BRUN LIE DETECTOR INTERFACE 


• 








1210 


* 


AS PART OF INITIALIZATION 


• 








1220 


* 




* 








1230 


* 


MEMORV USAGE - 


* 








1240 


* 


$315 - *34E (INCLUSIVE) 


* 








1250 


♦ 




* 








1260 


>¥>¥+++■¥>¥¥■¥¥¥¥¥+¥¥:¥++■¥:¥:¥■¥¥:¥¥¥¥++¥:¥*<■¥ 








1270 


* 












1280 


* 


INTERFACE EQUATES 










1290 


* 












1300 


USRUEC .EQ *A JSTART OF APPLESOFT USR VECTOR 








1310 


FLOAT .EQ *E2F2 ; CHANGE INTEGER 


TO FLOATING POINT UALUE 








1320 


CASS IN .EQ *C060 ; CASSETTE INPUT 


ADDRESS 








1330 


* 












1340 


* 


SET START OF PROGRAM TO PAGE 










1350 


* 


*3 WHERE IT IS OUT OF THE WAV 










1360 


* 












1370 




.OR *315 










1330 


* 












1390 


* 


INITIAL ENTRV 










1400 


* 


- SET UP USR VECTOR AND RETURN 








1410 


* 












1420 


JMPOP .EQ *4C ;OP CODE FOR JMP 








1430 


INIT .EQ * 




©315- 


A9 


4C 


1440 




LDA #JMPOP 




0317- 


85 


0R 


1450 




STA USRUEC 




0319- 


A9 


25 


1460 




LDA #ENTRV 




03 1B- 


35 


0B 


1470 




STA USRUEC-t-1 




031D- 


fl9 


03 


1430 




LDA .-ENTRV 




03 1F- 


85 


0C 


1490 




STA USRUEC +2 




0321- 


60 




1500 
1510 
1520 

1530 


* 
* 
* 


RTS 
STORAGE ALLOCATION 




0322- 


00 




1540 


I 


.DA #*-* J INNER LOOP COUNTER 


0323- 


00 




1550 


J 


.DA #+-* JOUTER LOOP COUNTER 


©324- 


00 




1560 


PULSES .DA #*-* INUMBER OF PULSES SEEN 








1570 


* 












1530 


* 


TIMING EQUATES 










1590 


* 


- LOOP FOR 16*255 TIMES 










1600 


* 












1610 


I START .EQ *FF 










1620 


JSTART .EQ *10 


/" N 








1630 


* 




\More___± 



Microcomputing, August 1981 87 



connect it to the Apple II r be sure that 
the lie detector operates properly in 
its unmodified form. 



Modifying the lie detector for inter- 
facing is simple. First, solder a minia- 
ture phono plug (the kind of plug that 



fits the cassette-in jack) to one end of 
a piece of two-conductor wire. Run 
the other end through a hole in the 



Listing 1 continued. 




















1640 


• LIE 


DETEt 


ITOR READ 










1650 


* - 


ALL 1 


JSER CALLS COME HERE 










1660 


¥ 














1670 


ENTRV 


. EQ 


* 


8325- 


R9 


00 




1680 




LDA 


#*0 ; CLEAR PULSE COUNTER 


S327- 


3D 


24 


03 


1690 




STA 


PULSES 


032H- 


R9 


10 




1700 




LDA 


#JSTART INITIALIZE OUTER 


032C- 


3D 


23 


03 


1710 




STA 


J ; LOOP COUNT 










1720 


CNTLO 


.EQ 


* ; OUTER LOOP ENTRV 


032F- 


R9 


FF 




1730 




LDA 


# I START ; INITIALIZE INNER 


0331- 


3D 




03 


1740 




STA 


I ; LOOP COUNT 










1 750 


CNTLI 


.EQ 


* ; INNER LOOP ENTRV 


0334- 


RD 


60 


ce 


1760 




LDA 


CASS IN ;TEST CASSETTE INPUT 


0337- 


10 


03 




1770 




BPL 


NOPULS ; BRANCH IF NO PULSE 


0339- 


EE 


24 


03 


1730 




INC 


PULSES ; COUNT PULSE SEEN 










1790 


NOPULS 


.EQ 


* 


033C- 


CE 




03 


1800 




DEC 


I 


033F- 


DO 


F3 




1310 




BNE 


CNTLI ILOOF C INNER) WHILE I NOT ZERO 


©341- 


CE 


23 


03 


1320 




DEC: 


J 


0344- 


D0 


E9 




1330 
1 340 


* 


BNE 


CNTLO JJLOOP (OUTER ) WHILE J NOT ZERO 










1350 


• CONVERT PULSES TO FLOATING 










1 860 


• POINT UALUE LIKE APPLESOFT 










1 870 


♦ EXPECTS and return 










1330 


* 






0346- 


R9 


00 




1390 




LDA 


#*0 


0348- 


RC 


24 


03 


1 900 




LD7 


PULSES 


034B- 


20 


F2 


E2 


1910 




JSR 


FLOAT 


034E- 


60 






1920 




RTS 




SVHPOL TRBLE 










USRUEC 000R 


FLORT 


E2F2 


CASS IN C060 


JMPOP 


004C 


INIT 


0315 


I 


0322 


J 


03 


523 


PULSES 


0324 


I START 00FF 


JSTRRT 0610 


ENTRV 


0325 


CNTLO 032F 


CNTLI 


0334 


NOPULS 


033C 







>CALL- 


-155 














*315.34E 
















©SIS- 


A9 


4C 


35 












OS 13- 


0A 


A9 


25 


35 


OB 


A9 


03 


85 


O320- 


QC 


60 


00 


00 


00 


A9 


00 


3D 


0323- 


24 


03 


A9 


10 


3D 


23 


03 


A9 


0330- 


FF 


3D 




03 


AD 


60 


CO 


10 


0338- 


03 


EE 


24 


03 


CE 


22 


03 


DO 


0340- 


F3 


CE 


23 


03 


D0 


E9 


A9 


00 


0343- 


AC 


24 


03 


20 


F2 


E2 


60 




*3D0G 


















Listing 2. A dump 


of the lie detector interface 


routine. 




















t p -LENGTH OF PULSE (CONSTANT) 

t f *TIME BETWEEN PULSES (VARIED TO CHANGE PITCH) 

Fig. 1. Lie detector audio output as seen by 
computer. 



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285 Bloomfield Avenue • Caldwell. N.J. 07006 



^327 



Microcomputing, August 1981 



case of the lie detector, and solder 
one conductor to each side of the 
speaker. 

Software Interface 

The audio oscillator output (as seen 
by the computer) is a varying pulse 
signal like that shown in Fig. 1. The 
pulse is constant, and the pitch is 
varied by changing the time between 
pulses. The simplest method of find- 



ing the relative pitch is to count the 
number of pulses in a given period. 
This is what the machine-language 
program in Listing 1 does. The rou- 
tine is designed to be used as a USR 
function from Applesoft in the same 
way that PDL is used to read the 
game paddles. When called from BA- 
SIC, the routine will return a number 
from to 255. Refer to Listing 1 for 
details of the routine's design. 



10 REM RPPLESOFT PROGRRM TO DEMONSTRATE LIE DETECTOR INTERFACE 

20 REM LAST REUISION U-OCT-80 INTERFACE 

100 GOSUB 40000: REM INITIALIZE 

110 REM SENSE-SCALE-DISPLAV LOOP 

120 S = USR CS>I REM READ RELET I UE STRESS 

130 REM S IS PASSED TO USR BUT IS NOT U<=:ED 

IS -'rZJ'r,' 6: IF S ' 38 THEN S = 38: REM SCRLE S T0 FIT LOW RES SCREEN 
150 REM PAINT METER BAR 

160 COLOR= RED: HLIN 0,S AT L 

170 COLOR= BLACK: HLIN S + 1,39 AT L 

130 GOTO 120: REM REPEAT FOREUER 

4O0O0 REM INITIALIZATIONS 

40010 M = CHR* \A:> 

40020 REM LOAD THE INTERFACE ASSEMBLV CODE 

40030 REM THE USR UECTOR IS SET UP AUTOMAT I CLV 

40040 PRINT D* + "BRUN LIE DETECTOR DRIUER" 

40050 RED = l: REM COLOR FOR METER BAR 

40060 L = 20: REM LINE TO PLACE METER BAR 

40070 GR : REM SET LOW-RES GRAPHIC MODE 

40999 RETURN 

Listing 3. A sample Applesoft program using the lie detector. 



To install the program in your sys- 
tem, first get into the monitor by typ- 
ing CALL - 155. The Apple II should 
beep and display the * prompt. List- 
ing 2 is a dump of the interface rou- 
tine. Type each line as shown in the 
dump, changing all dashes (-) to co- 
lons (:). To re-create the dump and 
check for entry errors, type 315.34E. 
When the program is entered correct- 
ly, type 3D0G to return to BASIC. 
From BASIC, type BSAVE LIE DE- 
TECTOR DRIVER,A$315,L$40 to 
save the routine to disk. 

Listing 3 shows a sample Applesoft 
program using the lie detector. A red 
lie-meter bar, which varies with skin 
resistance, is displayed using low res- 
olution graphics. ■ 

References 

Apple II Reference Manual, Apple 
Computer, Inc., 10260 Bandley Drive, 
Cupertino, CA 95014 
Applesoft II Programming Reference 
Manual, Apple Computer, Inc. 
S-C Assembler II Disk Version 3.2 Ref- 
erence Manual, S-C Software, PO Box 
5537, Richardson, TX 75080 



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^See List of Advertisers on page 194 



Microcomputing, August 1981 89 



Using an Apple to monitor water quality. 



Down by the River 

By Rolf A. Deininger, Richard L. Miller 

and Paul J. Capano 




Photo 1. Martek water quality monitor and Apple microcomputer on a bridge over the Huron River in 
Ann Arbor, Michigan. 

Microcomputing, August 1981 



Automatic sensors used to monitor 
water quality will quickly gather 
much data. This gives you a great 
deal of flexibility: you can monitor a 
location over a period of time, a cross 
section of a river or different depths 
at a single location in a lake. 

But large amounts of data can cre- 
ate significant handling problems. So 
instead of reading the data from the 
instruments, keypunching them and 
analyzing them later, we decided to 
use a microcomputer. 

The advantage of this system is that 
data can be collected continuously 
and recorded in machine-readable 
form. No need to read the meters, 
write the values in notebooks and 
then keypunch them later for pro- 
cessing or storage. The data on the 
disk can be transferred to a larger 
computer system using the commu- 
nications interface and a modem, and 
we do this routinely. 

This small microcomputer system 
has extended our abilities to monitor 
water quality significantly and does it 
very cost-effectively. 

The System 

The computer is an Apple II, and 
the monitor is from Martek Instru- 
ments. Photo 1 shows the actual set- 
up, on a bridge over the Huron River 
in Ann Arbor. The monitor and dis- 
play are on the top shelf; the Apple, 
amplifier, disk drive and cables are 
on the middle shelf; and the power 
supply is on the bottom shelf. 

Photo 2 shows the actual sensors 
which are lowered into the water. 
From left to right are the oxygen sen- 

Address correspondence to Rolf A. Deininger, Pro- 
fessor of Environmental Health, The University of 
Michigan, Ann Arbor, MI 48109. 



sor, the temperature sensor, the con- 
ductivity sensor and the pH sensor. 
The unit also has a depth sensor, 
which was not used. 

The power source for the Apple 
and the display is a 12- volt recrea- 
tional-vehicle battery connected to a 
100- watt power inverter (Radio Shack 
Cat. No. 22-31) which produces 1 10 V 
ac. Our Apple draws about 0.3 amps 
at 110 V, and increases to about 0.4 
amps during disk operations. The 
Sanyo display draws a little less than 
0.3 amps at 110 V. Due to inefficien- 
cies in the inverter, the battery drain 
is about 7 amps at 12 V. For a few 
hours of operation, the battery shown 
is sufficient; for longer times you'll 
need a larger battery. (Occasional use 
of the display also reduces power re- 
quirements.) 

The Martek water quality monitor 
continuously monitors the tempera- 
ture, the dissolved oxygen, the pH 
and the conductivity of the river wa- 
ter and displays the values on the 
panel meters. At a recorder output, 
all four signals are continuously 
available and range from to 500 
mV. These signals are then amplified 
by a factor of about eight using four 
LM308NA operational amplifiers. 

An analog/digital (A/D) converter 
(AI-02 from Interactive Structures, 
Inc., Bala Cynwyd, PA) outputs 
digital voltage readings. The voltages 
sampled by the system were cali- 
brated using known water samples 
and calibration signals available on 
the Martek monitor. We've written a 
simple program that will check the 
sensors for a predetermined number 
of samples at given time intervals (see 
Listing 1). 

The program in Listing 2 produces 
a printout of data stored on disk. Data 
gathered one afternoon, stored on 
disk and later printed at our office us- 
ing this program is shown in the Sam- 
ple run. 

Program Notes 

The program in Listing 1 actually 
begins at line 1000, which sets the 
base addresses for the A/D converter 
(in slot 7 of our Apple). Lines 1010 
through 1040 set the amplification 
and conversion factors for the four 
channels. Statement 1090, together 
with 160, produces the approximate- 
ly desired sampling interval. 

Since the Martek has several 
ranges for measurement of dissolved 
oxygen and conductivity, statements 
1140 through 1190 are needed to set 
the desired range for each. Statement 



1230 activates a scrolling window. 
The program goes to line 50. Lines 60 
through 100 cause the A/D converter 
to initiate a conversion, read the con- 



verted values and round them to the 
first decimal place. Lines 1 10 through 
150 print the data onto the monitor 



screen. 



Listing 1. Computer program in APPLESOFT for operating the system. 



J LOAD 
3LIST 



WQ MONITOR 



10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

110 

120 

130 

140 

150 

160 

170 

180 

190 

200 

2 1 

220 

230 

240 

250 

260 

270 

280 

300 

310 

1000 

1010 

1020 

1030 

1040 

1050 

1060 

1070 

1080 

1090 

1100 

1110 

1120 

1130 

1140 

1150 

1160 

1170 

1180 

1190 

1200 

1210 

1220 

1230 

1240 

1250 



REM WATER QUALITY 

REM WRITTEN BY R 

DIM SRC 600 y 4 ) 

GOTO 1000 
SN - SN f 1 

FOR I a 1 TO 4 

POKE APlvI 
R ■ PEEK ( A ) * 
SRC SN,I ) - INT 
NEXT I 



MONITORING 
DEININGER 



SYSTEM 
MAY 80 



* 



3: 



9: 

16 

*.. \.i 
'•>o 

<C 7 



I 



PRINT 
PRINT 
PRINT 
PRINT 
PRINT 
1 



SN 



NS 



"N" GOTO 300 
C 4 ) 



n 



OPEN 
D*5 M WRITE 
LOG* 
NS 

TO 
1,1 
1,3 



•t 



■ 1 
SRC 
SRC 



" CLOSE 
PRINT " 



HTAB 
HTAB 

HTAB 
HTAB 
HTAB 

FOR 
IF S 

IF Sl/t ■ 
Dt - CHR* 
PRINT D1 
PRINT 
PRINT 
PRINT 
FOR I 
PRINT 
PRINT 
NEXT I 
PRINT Dt? 
HTAB 15: 
STOP 
A ■ 
AFC 1 
AFC 3 
CVC 1 
CVC 3 ) 

PRINT 

INPUT 

PRINT 

INPUT 
DLAY = 

PRINT 

INPUT 

PRINT 

INPUT 

PRINT 

INPUT 
CVC 4 ) = 

PRINT 

INPUT 
CVC 2 > - CVC 2 ) 
SN - 01 CALL 

PRINT "LOCATION 

PRINT "SAMPLE* 



19*6 
C C R f 

sn; 

SRC SN 



CVC I ) / AFC I ) 
♦ 05 ) * 10 ) / 10 



SRC 



i >; 

,2 )5 
SRC SN»3)» 

SRC SN,4 ) 

to dlay: next 

THEN 50 



SN 



;loc* 

" JLOC* 



NS 

,\ PRINT SRC 
>t PRINT SRC 



1,2 
1,4 



" ?L0C* 
♦DONE* 



* ♦ 



♦ ♦ 



it 



) 
) 
) 



ii 



14592: API ■ 
7.91 1AF< 2 ) 

7*91 : AFC 4 ) 

♦ 0234:CVC 2 

♦ 0756:CVC 4 
ENTER NAME 

LOC* 

"ENTER SAMPLING 

SECS 

700 * SECS 

"HOW MANY SAMPLES 

NS 

"SAVE 



i: 



A i 

- 7*91 

- 8.0 
) = *0199 
) = *09 

OF SAMPLING 



REM SLOT 7 ADDRESSES 



STATION" 



INTERVALC 



SECS )" 



TO BE TAKEN" 



THE DATA ON DISKC Y/N >" 



"ENTER CONDUCTIVITY RANGE SELECTED" 
CR: IF CR > 100 OR CR < 2*5 THEN 1140 
CVC 4 ) * CR / 50 

DISS OXYGEN RANGE SELECTED" 
DR > 20 OR BR < 2 THEN 1170 
* DR / 10 
- 936 

5 LOC*: PRINT : PRINT 

OX TEMP COND" 



4 ) 
"ENTER 

dr: IF 



PH 



DIS 



POKE 
GOTO 
END 



34,4 



50 



10 
11 
20 
30 
40 



Listing 2. Program that produced the Sample run. 



REM MARTEK DATA READER 
DIM SRC 600,4 ) 
D* = CHR* C 4 ) 
PRINT "ENTER NAME OF FILE" 
INPUT FI* 




Microcomputing, August 1981 91 



81 
DISK DRIVES 

5V4" flippy with case and power supply 

One Drive $ 320 

Two Drive $ S20 

Three Drive $ 900 
Four Drive 

8" with case and power supply 

One Drive 

Two Drive S 940 

Three Drive 

Four Drive 



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Fort Worth TX 76107 

817-731-7412 ^346 



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Texas residents add 5% sales tax. 
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Central 80% of CRT. 550 Lines Minimum beyond central 80% 
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100 Foothill Blvd. 
San Luis Obispo, CA 
93401 InCaL call 
(800)592-5935 or 

(805)543-1037 



m 



Wtt 



^172 



Listing 2 continued. 



50 
60 
70 
BO 
90 
100 

110 

120 

130 

140 

150 

160 

170 

180 

190 

200 

210 

220 

230 

240 



PRINT 
PRINT 

INPUT 
INPUT 
FOR I 
INPUT 
INPUT 
NEXT 
PRINT 
PRINT 
PRINT 
FOR I 
UTAH 
HTAB 
HTAB 
HTAB 
HTAB 
NEXT 
HTAB 
END 



D*? "OPEN 



D* 5 "READ 

L0C* 

NS 

* 1 TO NS 



ti 



(• 



FI* 

ri* 



3R< 



i*i >: 



SR< 1*3 



>: 



INPUT 
INPUT 



SRC 
SR< 



If 2 ) 
1*4 ) 



I 



it 



I. 



•i 



;loc* 



ocation: 

: PRINT 
"SAMPLE* PH 
■ 1 TO NS 
PRINT I? 
PRINT SRC I* 1 )? 
PRINT SRC I* 2 )r 
PRINT SRC If 3 )f 



BIS OX 



TEMP COND 



n 



3: 
?: 
16: 
23: 



PRINT SRC If 4 ) 



29 

I 

15t PRINT 



ii 



♦ ♦ 



♦DONE* 



♦ ♦ 



H 



3RUN 










ENTER NAME 01 


" FILE 






?HUR0N RIVER 


BRIDGE C 6/24/80-1PM ) 


location: hur 


:0N RIVER BRIDGE C 6/2 


4/80-1PM ) 


SAMPLE* 


PH 


DIS OX 


TEMP 


COND 


1 


8*3 


8.1 


21 .8 


56.2 


2 


8*3 


8*1 


21.8 


56.2 


3 


8*3 


8.1 


21.8 


56.2 


4 


8.3 


8.1 


21.8 


56.2 


5 


8*3 


8.1 


21 .8 


56.2 


6 


8*3 


8.1 


«.. 1 ♦ o 


56.2 


7 


8*3 


8.1 


21.8 


56.2 


8 


8*3 


8.1 


21.8 


56.2 


9 


8*3 


8.1 


21.8 


56.2 


10 


8.3 


8.1 
. . .DONE 

Sample run. 


21.8 
♦ . « 


56.2 



plMi^MfMlMPIlflf^MIPJ 



TAR HEEL SOFTWARE SYSTEMS 

"Affordable Software for Small Business" 
PROUDL Y ANNOUNCES 

REAL ESTATE BOOKKEEPING SYSTEM 

a disk-based fully-integrated system including 
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Free continuing update service included. 
Minimum hardware: TRS-80 Model I, 32K, 
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SYSTEMS, INC. 

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BURLINGTON. NORTH CAROLINA 27215 



UMI^MMMIMMPM^MI^M 




Photo 2. Sensor assembly for dissolved oxygen, 
temperature, pH value and conductivity. 



92 Microcomputing, August 1981 



11 



NIBBLE IS TERRIFIC 

(Fop Your Apple) 



91 



nibble 

TH< RtFEflfUCf EQB APPIE COMPUTING 



NIBBLE 18: 7Yi? Reference for Apple computing! 



IS: One of the Fastest Growing new Magazines in 
the Personal Computing Field. 




18: Providing Comprehensive, Useful and 
Instructive Programs for the Home, Small Business, and 
Entertainment. 



IS: A Reference to Graphics, Games, Systems 
Programming Tips, Product News and Reviews, Hardware 
Construction Projects, and a host of other features. 



IS: A magazine suitable for both the Beginner and 
the Advanced Programmer. 

Each issue of NIBBLE features significant new Programs of Commercial Quality. Here's 
what some of our Readers say: 

- "Certainly the best magazine on the Apple II" 

- "Programs remarkably easy to enter" 

- "Stimulating and Informative; So much so that this is the first computer magazine I've 
subscribed to!" 

- "Impressed with the quality and content." 

- "NIBBLE IS TERRIFIC!" 

In coming issues, look for: 

D Stocks and Commodities Charting □ Assembly Language Programming Column 

□ Pascal Programming Column □ Data Base Programs for Home and Business 

□ Personal Investment Analysis □ Electronic Secretary for Time Management 

□ The GIZMO Business Simulation Game 

And many many more! 

NIBBLE is focused completely 
on the Apple Computer systems. 

Buy NIBBLE through your local 
Apple Dealer or subscribe now with 
the coupon below. 

Try a NIBBLE! 



iOTE 

irst Class or Air Mail is required for all APO. FPO and all foreign addresses 
nth the following additional amounts 

Lurope $32 00; Mexico and Central America $21 00 South America $32 00. 
liddle East $35 00. Africa North $32 00. Central $43 00. South $43.00: Far 
Last. Australia $43 00. Canada $18.00. APO FPO 57 50 

kll payments must be in US funds drawn on a US bank 

1980 by MICRO-SPARC . INC Lincoln. Mass. 01773. All rights reserved 
Apple II is a registered trademark of Apple Computer Company 



nibble 



^286 



Box 325. Lincoln, MA. 01773 (617) 259-9710 

I'll try nibble! 

Enclosed is my $17.50 (for one year). 
(Outside U.S., see special rates on this page.) 

□ check □ money order 

Your subscription will begin with the next issue published after 
receipt of your check/money order. 



Name 



Address. 




Are you looking for. 



or 



When you subscribe to a magazine, you want to get REAL 
SOLID INFORMATION, not just a giant catalog of ads 
every month . . . and mostly the same ads, if you've noticed. 
Kilobaud Microcomputing has the meat: feature articles 

written by the most knowledge- 
able people in the field, yet writ- 
ten for the relative newcomer to 
computing. Kilobaud Microcomputing 
has more articles than any other maga- 
zine in the field ... by a wide margin 
. . . regardless of fatness. In 1980 Kilo- 
baud Microcomputing published 409 
articles . . . and that included a wealth 
of programs which you could use. 

Compare that with 133 paltry arti- 
cles in Brand B, the "Fat Albert" 
of the computer field. You can 
get far more from your computer 
if you can really understand it, 
which is where the simple articles 
in Kilobaud Microcomputing 
come in. You don't need a science 
degree to get through it like some 
magazines I could mention. The 
practical reviews of both hardware 
and software in Kilobaud Micro- 
computing can save you a bundle 
... far more than the cost of a 
subscription . . . even for life. The 
wealth of programs give you things you 
can do with your computer . . . again at a 
fraction of the cost of buying the same 
program over the counter. Further, the 




articles on programs help you learn how to write and modify 
programs that you have to do yourself. 

When you subscribe to a magazine, you want to pay for 
the information, not a bunch of ads. The advertisers are 
already paying for them so why should you? Kilobaud 
Microcomputing has been running around 40% advertising 
while Brand B has been running 60-70% , making fat issues, 
but with little real information for you. 

You want to learn about computers as fast as you can. The 
editors of Kilobaud Microcomputing are 
under orders (pain of death or 
worse) to keep the material as sim- 
ple as possible so new comers will 
be able to learn about computers 
as quickly as possible. Kilobaud 
Microcomputing covers all types 
of microcomputers, including (to 
some extent) the TRS-80 though 
this is covered overwhelmingly in 
80 Microcomputing, a sister pub- y 
lication. 

At $2.95 a copy, Kilobaud 
Microcomputing is the best infor- 
mation buy you'll find. At $25 a 
year (you save $10.40 off the 
newsstand price) you're investing 
in the most valuable library of 
microcomputing you can buy . . . 
2,960 pages in 1980! 



oat. 



□ So, please bill me $25 for one year's subscription 

to Kilobaud Microcom\mting. 



Canadian $27/1 year only, US funds. 
Foreign $35/1 year only, US funds. 
Please allow 4-6 weeks for delivery. 



name 
street 
city _ 



Kilobaud Microcomputing • Box 997 • Farmingdale NY 11737 

TT 



is a division of 



j^ 



13 Peterborough NH 03458 



94 Microcomputing, August 1981 




state 



The price for this interface can't be beat. 



Apple to Selectric for 83 Cents 



By Charles Behrens 



For 83 cents and some intriguing 
tinkering, your Apple can control 
any peripheral device with a serial in- 
put port. Of course, there are many 
interface cards on the market de- 
signed to do just this, but they usually 
cost several hundred dollars. Who 
needs that when every Apple already 
has what it takes! 

PET, Atari, Ohio Scientific and 
other microcomputer owners should 
also take note: the technique can be 
applied to virtually any system. The 
program listings supplied here are 
written in 6502 assembly language 
and can be readily adapted. 
To test my new hardware addition, 



I wrote a short software routine to 
control an IBM Selectric typewriter/ 
printer. It works beautifully. 

The Apple II was designed for easy 
interface to the outside world. All of 
the proper signals for controlling pe- 
ripherals were brought out to the Ap- 
ple II's ports, and they are just aching 
to be harnessed. Here's how to take 
maximum advantage of what the folks 
at Apple have already provided. 

Interface Construction 

To create the interface, you must 
do four things: 

•Write a software routine to trans- 
late the Apple's internal American 




Photo 1 . The author's system with Carterfone S15B Selectric I at left. Notice the "customized" paper dis- 
penser from the local hardware store. (All photos by Michael La Pointe.J 



Standard Code for Information Inter- 
change (ASCII) coded data from a 
parallel format to the proper serially- 
coded format that the Selectric can 
use. 

•Output this serial data to a latched 
port on the game paddle I/O connec- 
tor. 

• Build a simple, one-transistor cir- 
cuit to supply the needed transistor- 
transistor-logic (TTL) to RS-232C 
voltage conversions. (See reference 1 
for background on steps 1 and 3.) 

•Add + 12 and - 12 V supply volt- 
ages to the two unused pins on the 
game paddle connector. 

The best reward is that the only 
costs are for a little one-transistor cir- 
cuit. Not only that, but the little cir- 
cuit fits inside a case like the one on 
the plug of the game paddle control- 
lers. How convenient can you get! 

Inside the Selectric 

To understand the software, you 
must first understand the coding for- 
mat that IBM designed into its print- 
ers. 

The IBM Selectrics use a six-bit 
code. You might ask how this can be. 
Given that there are 128 unique char- 
acters in the seven-bit ASCII code, 
how can just six bits generate enough 
different symbols to represent all of 
the letters needed? It's an old trick 
that the inventors of the modern 
typewriter developed. They were 
faced with the dilemma: With the 
great number of characters used in 



Address correspondence to Charles Behrens, PO 
Box 233, Kingston, RI 02881. 



Microcomputing, August 1981 95 



CHARACTER ASCII CORR BCD EBCD 



NUL 


80 


7F 


7F 


7F 


SOH 


81 


7F 


7F 


7F 


STX 


82 


7F 


7F 


7F 


ETX 


83 


7F 


7F 


7F 


EOT 


84 


FC 


FC 


FC 


ENQ 


85 


7F 


7F 


7F 


ACK 


86 


7F 


7F 


7F 


BELL 


87 


7F 


7F 


7F 


BACK SPACE 


88 


5D 


5D 


5D 


TAB 


89 


2F 


2F 


2F 


LINE FEED 


8A 


6E 


6E 


6E 


VERT. TAB 


8B 


7F 


7F 


7F 


FF 


8C 


7F 


7F 


7F 


CAR. RET. 


8D 


6D 


6D 


6D 


SO 


8E 


7F 


7F 


7F 


SI 


8F 


7F 


7F 


7F 


DLE 


90 


7F 


7F 


7F 


DC1 


91 


7F 


7F 


7F 


DC2 


92 


7F 


7F 


7F 


DC3 


93 


7F 


7F 


7F 


DC4 


94 


7F 


7F 


7F 


NAK 


95 


7F 


7F 


7F 


SYN 


96 


7F 


7F 


7F 


ETB 


97 


7F 


7F 


7F 


CAN 


98 


7F 


7F 


7F 


EM 


99 


7F 


7F 


7F 


SUB 


9A 


7F 


7F 


7F 


ESC 


9B 


7F 


7F 


7F 


FS 


9C 


7F 


7F 


7F 


GS 


9D 


7F 


7F 


7F 


RS 


9E 


7F 


7F 


7F 


US 


9F 


7F 


7F 


7F 


SPACE 


A0 


40 


40 


40 


• 


Al 


81 


75 


75 


II 


A2 


49 


38 


34 


# 


A3 


70 


B4 


B4 


$ 


A4 


04 


F5 


F5 


% 


A5 


08 


68 


68 


& 


A6 


68 


C3 


C3 


/ 


A7 


C9 


58 


58 


I 


A8 


34 


64 


64 


) 


A9 


64 


54 


54 


* 


AA 


38 


04 


04 


+ 


AB 


13 


34 


43 


i 


AC 


3B 


F6 


F6 


— 


AD 


B7 


81 


81 


• 


AE 


51 


B7 


B7 


/ 


AF 


87 


E2 


E2 





BO 


E4 


D4 


D4 


1 


Bl 


C6 


AO 


AO 


2 


B2 


90 


90 


90 


3 


B3 


FO 


FO 


FO 


4 


B4 


84 


88 


88 


5 


B5 


88 


E8 


E8 


6 


B6 


D8 


D8 


D8 


7 


B7 


E8 


B8 


B8 


8 


B8 


B8 


84 


84 


9 


B9 


B4 


E4 


E4 


• 
• 


BA 


6B 


08 


08 


• 
i 


BB 


EB 


70 


70 


< 


BC 


7F 


7F 


10 


= 


BD 


93 


20 


20 


> 


BE 


7F 


7F 


38 


? 


BF 


07 


62 


62 



@ 


CO 


70 


82 


82 


A 


CI 


79 


23 


23 


B 


C2 


76 


13 


13 


C 


C3 


7A 


73 


73 


D 


C4 


2A 


OB 


OB 


E 


C5 


4A 


6B 


6B 


F 


C6 


73 


5B 


5B 


G 


C7 


23 


3B 


3B 


H 


C8 


26 


07 


07 


I 


C9 


19 


67 


67 


J 


CA 


43 


61 


61 


K 


CB 


1A 


51 


51 


L 


CC 


46 


31 


31 


M 


CD 


61 


49 


49 


N 


CE 


52 


29 


29 


O 


CF 


45 


19 


19 


P 


DO 


OB 


79 


79 


Q 


Dl 


5B 


45 


45 


R 


D2 


29 


25 


25 


S 


D3 


25 


52 


52 


T 


D4 


02 


32 


32 


U 


D5 


32 


4A 


4A 


V 


D6 


31 


2A 


2A 


w 


D7 


75 


1A 


1A 


X 


D8 


62 


7A 


7A 


Y 


D9 


67 


46 


46 


z 


DA 


54 


26 


26 


L. BRACK. 


DB 


7F 


7F 


7F 


B. SLASH 


DC 


7F 


7F 


7F 


R. BRACK. 


DD 


7F 


7F 


7F 


CIRCUMFLEX 


DE 


7F 


7F 


7F 




DF 


7F 


01 


01 


SPACE 


EO 


40 


40 


40 


a 


El 


F9 


A3 


A3 


b 


E2 


F6 


93 


93 


c 


E3 


FA 


F3 


F3 


d 


E4 


AA 


8B 


8B 


e 


E5 


CA 


EB 


EB 


f 


E6 


F3 


DB 


DB 


g 


E7 


A3 


BB 


BB 


h 


E8 


A6 


87 


87 


i 


E9 


99 


E7 


E7 


J 


EA 


C3 


El 


El 


k 


EB 


9A 


Dl 


Dl 


1 


EC 


C6 


Bl 


Bl 


m 


ED 


El 


C9 


C9 


n 


EE 


D2 


A9 


A9 


o 


EF 


C5 


99 


99 


P 


FO 


8B 


F9 


F9 


q 


Fl 


DB 


C5 


C5 


r 


F2 


A9 


A5 


A5 


s 


F3 


A5 


D2 


D2 


t 


F4 


82 


B2 


B2 


u 


F5 


B2 


CA 


CA 


V 


F6 


Bl 


AA 


AA 


w 


F7 


F5 


9A 


9A 


X 


F8 


E2 


FA 


FA 


y 


F9 


E7 


C6 


C6 


z 


FA 


D4 


A6 


A6 


L. BRACE 


FB 


7F 


7F 


7F 


1 


FC 


7F 


7F 


7F 


R. BRACE 


FD 


7F 


7F 


7F 


WAVE 


FE 


7F 


7F 


7F 


RUB 


FF 


7F 


7F 


7F 



Table 1. ASCII -to-Selectric conversion table. Any Selectric can support all three codes, depending on which type element is installed by the user (reference 1). 



96 Microcomputing, August 1981 



9580- 
9588- 
9590- 
9598- 
95A0- 
95A8- 
95B0- 
95B8- 
95C0- 
95C8- 
95D0- 
95D8- 
95E0- 
95E8- 
95F0- 
95F8- 



7F 
5D 
7F 
7F 
U0 

Dk 
8U 
82 
07 
79 
7A 
kO 
87 
F9 
FA 



7F 
2F 
7F 
7F 
75 
5U 
AO 
El» 
23 
67 
U5 
U6 
A3 
E7 
C5 
C6 



7F 
6E 
7F 
7F 
3U 
OU 
90 
08 
13 
61 
25 
26 
93 
El 
A5 
A6 



7F 
7F 
7F 
7F 
BU 
U3 
FO 
70 
73 
51 
52 
7F 
F3 
Dl 
D2 
7F 



8B 
7F 
7F 
7F 
F5 
F6 
88 
10 
OB 
31 
32 
7F 
8B 
Bl 
B2 
7F 



7F 
6D 
7F 
7F 
68 
81 
E8 
20 
6B 
U9 
UA 
37 
EB 
C9 
CA 
01 



7F 
3E 
7F 
7F 
C3 
B7 
D8 
38 
5B 
29 
2A 
76 
DB 
A9 
AA 
52 



7F 
7F 
7F 
7F 
58 
E2 
B8 
62 
3B 
19 
1A 
7F 
BB 
99 
9A 
20 



Table 2. This is the cross-reference table I am 
currently using with my Selectric typewriter/ 
printer. I have adapted some of the characters 
for special uses, so this table does not exactly 
correspond with Table 1. 



written print, how does one make an 
efficient keyboard for ten-fingered 
humans? As a solution, the shift key 
was invented. Suddenly only half as 
many separate keys were needed to 
create the entire character set. When 
the Teletype came along, the design- 
ers realized that the same trick could 
be used to speed up transmitted elec- 
tronic information. 

Naturally, when IBM Selectrics 
were outfitted as data terminals, the 
old dog used the same old trick. And 
it is this same trick that our program 
uses to generate any character de- 
sired. When the Selectric is to be sent 
an uppercase letter, a shift-up must 
precede it. Any letter sent from then 
on will be in uppercase until a shift- 
down code is transmitted. The soft- 
ware technique for doing this will be 
described shortly. 

Next, you need to understand that 
IBM Selectrics use three different six- 
bit codes. The reason for this is that 
there are three different methods of 
configuring the letters on the type 
element. The style of type element in- 
stalled in the machine determines 
which code is to be used. If the wrong 
code is transmitted to the Selectric, it 
will print nonsense. The codes used 
are extended binary-coded decimal 
(EBCD), binary-coded decimal (BCD) 
and correspondence code. (See Table 

1.) 
EBCD and BCD printheads are fine 

for utility printing, but if you need to 
do a great deal of word processing, 
then get a correspondence-code ele- 
ment. It offers a greater variety of 
character fonts (e.g., script, oversize, 
special characters, etc.). Convenient- 
ly, every style may be used on the 
same machine. It is not necessary to 
own separate typewriters; just differ- 
ent type elements. 

By relying on a software method of 
controlling the Selectric, three differ- 



ent look-up tables can be created to 
handle each style of code. This would 
be expensive to do with a hardware 
approach. But with software, you can 
load any of the codes separately. This 
offers the versatility of having all 
three while only tying up a minimal 
amount of memory space for one at a 
time. 

Now that these points are under- 
stood, let's move into the workings of 
the software. 

The Program 

The 6502 assembly-language rou- 
tine (see Listing 1) is used for translat- 
ing the Apple's internal character 
data to the needed serial code (refer- 
ences 2 and 3). The program is short 
enough to fit in even a 16K Apple. 
This program will be called in every 
mode of the Apple's operation. Any- 
thing that can be displayed on the 
video screen can be printed. In other 
words, it may be used for word pro- 
cessing, BASIC program listings, 
monitor listings and even to obtain 
hard copies of program output. 

The first duty of the program is to 
intercept the desired ASCII character 
before it is sent to the usual output 
routine in the Apple II's Monitor. 
Normally, this is the COUT1 routine 
at $FDF0 (the "$" sign indicates a 
hexadecimal number), used for dis- 
playing output on the video screen. 
When a character is to be output, the 
routine at $FDFE named COUT reads 
the values at $36 and $37 to deter- 
mine the address of the output rou- 
tine. Because the output routine is in- 
directly called, it is easy to divert the 
program flow by substituting a new 
address. This is a technique called 
vectoring. 

The routine listed here loads its 
own beginning address to locations 
$36 and $37, instead of the address 
for COUT1. In this way, COUT will 
vector to the printing routine when it 
tries to output a character. For conve- 
nience, the print routine branches to 
COUT1 after printing so that the 
character is also displayed on the vid- 
eo screen. 

Once the printing routine has been 
called, its first step is to save all of the 
working registers in memory. This is 
so that everything will be intact when 
the routine returns from the call. 

At the beginning of the routine, the 
accumulator contains the desired 
ASCII character. The code for this 
character is also stored separately in 
location $FC of page zero for easy re- 
call. Execution then proceeds into the 



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^289 



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Microcomputing, August 1981 97 



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^272 



ELUS COMPUTING 

SOFTWARE TECHNOLOGY 



heart of the program. 

A check is made to determine if a 
carriage return is to be output. If so, 
then three things must happen. First, 
the Carriage Return must be preced- 
ed with a Shift-Up command. Sec- 
ond, a carriage return character must 
be sent. Third, an extra long delay is 
needed to give time for the carriage to 
physically move back to the start of 
the next line before trying to print the 
next character. 

The extra shift-up is needed to 
work properly with the word proces- 
sor program, Apple Writer. Other- 
wise, the Selectric sometimes will not 
properly decode the carriage return 
character. Obviously word process- 
ing with Apple Writer is not the only 
use for the printer. During those 
other times, it is necessary to replace 
the extra shift-up character to a null 
character to prevent errors. Change 
the $9C in location $9DF7 of the pro- 
gram to a $FF and you'll be all set. 

The indexed addressing mode of 
the 6502 is invaluable for determin- 
ing the properly cross-referenced Se- 
lectric code. Knowing that the ASCII 



characters are represented by the val- 
ues $80 through $FF, the ASCII-to-Se- 
lectric cross-referencing table is load- 
ed into locations $80 through $FF of a 
page in memory immediately follow- 
ing the program. (See Table 2.) The 
page number containing the look-up 
table is then set as the base address of 
the indexed addressing instruction. 

The value of the needed ASCII 
character is then loaded into the Y 
register. By adding the value of the Y 
register to the base address, the right 
code in the look-up table can be 
found with just one instruction! This 
value is then tucked away for safe- 
keeping in location $FB of page zero. 

Once the Selectric character code is 
obtained, the next step is to figure out 
whether it is an upper or lowercase 
letter. Not only that, but also whether 
or not the last letter sent was of the 
same case. This is done by comparing 
the most-significant bit (MSB) of the 
character code with the MSB in loca- 
tion $FA. The MSB denotes the case 
of the letter, and location $FA holds 
the case of the last letter sent. 

If the new character is not of the 



Listing 1. This 6502 assembly-language routine is the foundation of the Apple /Selectric interface 
described in this article. The same logic will also work with Atari, PET, Ohio Scientific and other 
6502-based micros with only minor changes. Due to vectoring, it can be located in any convenient 
section of memory. Note: change location $94F7 to $FF when not using the Apple Writer word 
processor. (See text.} 



9UDU- 
9UD6- 
9UD8- 
9UDA- 
9UDC- 
9UDF- 



9UE0- 

9«*E1- 
9UE2 
9UEU- 
9UE6- 



94E9- 
9UEB- 
9UED- 
9UEE- 
9UEF- 



9UF0- 
9UF2- 
9UFU- 
9UFG- 
9UF8- 
9i*FB- 
9UFD- 
9500- 



A9 
85 
A9 
85 
20 
60 



1+8 
08 
86 
8U 
20 



A6 
Ai» 
28 
68 
60 



85 
C9 
DO 
A9 
20 
A9 
20 
F0 



E0 
36 
9i» 
37 
51 



A8 



FE 
FF 
F0 9U 



FE 
FF 



FC 
8D 
OC 
9C 
27 
ED 
27 
UB 



95 
95 



LDA 
STA 
LDA 
STA 
JSR 
RTS 



PHA 
PHP 
STX 
STY 
JSR 



LDX 
LDY 
PLP 
PLA 
RTS 



STA 
CMP 
BNE 
LDA 
JSR 
LDA 
JSR 
BEQ 



#$E0 

$36 

#$9U 

$37 

$A851 



♦♦PRINTER OUTPUT ROUTINE 

LOAD $9UE0 AS VECTOR BRANCH FOR 'COUT' 
LOW BYTE IN $36 

HIGH BYTE IN #37 
SET D.O.S. VECTORS 



**SAVE-SAVE ALL REGISTERS 



$FE 
$FF 
$9UF0 



$FE 
$FF 



JUMP TO **BEGIN 



**RESTORE-RESTORE ALL REGISTERS 



$FC 

#$8D 

$9502 

#$9C 

$9527 

#$ED 

$9527 

$95UD 



RETURN 



950,2- 


A8 




TAY 




9503- 


B9 


00 95 


LDA 


$9500 


9506- 


85 


FB 


STA 


$FB 


9508- 


29 


80 


AND 


#$80 


950A- 


C5 


FA 


CMP 


$FA 


950C- 


85 


FA 


STA 


$FA 


950E- 


F0 


0E 


BEQ 


$951E 


9510- 


90 


07 


BCC 


$9519 



RETURN TO CALLING PROGRAM 

**BEGIN-THE MAIN PROGRAM 

STORE THE ASCII CHARACTER IN $FC 

CHECK TO SEE IF IT IS A CARRIAGE 

IF NOT, BRANCH TO **L00KUP 

ELSE, OUTPUT A 'SHIFT UP' 

JUMP TO **SERIAL 

THEN A CARRIAGE RETURN 

JUMP TO **SERIAL 

BRANCH TO LONG DELAY 



**L00KUP-CR0SS REFERENCE ASCII TO SELECTRIC 
USE Y-REGISTER AS OFFSET WITHIN TABLE 
LOAD FROM TABLE 
STORE FOR SAFE KEEPING 

**CASE-CHECK CURRENT CASE AGAINST LAST 
MASK OFF BITS 0-6 

CHECK M.S.B. AGAINST LAST CHARACTER SENT 
SAVE NEW M.S.B. 

IF SAME CASE, BRANCH TO **PREP 
NEED A 'SHIFT UP'? 

. More 
**SH)FT DOWN-SEND A SHIFT DOWN 




Microcomputing, August 1981 



Listing 1 continued 










9512- 
951U- 
9517- 


A9 
20 
F0 


9F 
27 
05 


95 


LDA 
JSR 
BEQ 


#$9F 

$9527 

$951E 


LOAD SHIFT DOWN CODE 
JUMP TO **SERIAL 
BRANCH TO **PREP 

**SHIFT UP-SEND A SHIFT UP 


9519- 
951B- 


A9 
20 


9C 
27 


95 


LDA 
JSR 


#$9C 
$9527 


LOOAD SHIFT UP CODE 
JUMP TO **SERIAL 
**PREP-PREPARE CHARACTER FOR SERIAL OUTPUT 


951E- 


A5 


FB 




LDA 


$FB 


RELOAD CHARACTER CODE 


9520- 


09 


80 




ORA 


#$80 


SET M.S.B. FOR USE AS 'STOP BIT 1 


952Z- 


1Q 


17 


95 


JSR 


$9527 


JUMP TO **SERIAL 


9525- 


FO 


31 




BEQ 


$9558 


BRANCH TO **VIUEO 
**SERI AL-SERIALIZE AND OUTPUT CHARACTERS 


9527- 


A2 


09 




LDX 


#$09 


SET COUNTER 


9529- 


86 


FD 




STX 


$FD 


STORE COUNTER IN $FD 


952B- 


18 






CLC 




CLEAR CARRY BIT TO USE AS "START BIT 1 
**OUTPUT-OUTPUT BITS 


952C- 


90 


08 




BCC 


$9536 


BRANCH TO **ZERO IF CARRY CLEAR 
**ONE-OUTPUT A LEVEL ONE 


952E- 


8D 


59 


CO 


STA 


$C059 


TURN ON 'AN#0' PORT 


9531- 


20 


hi 


95 


JSR 


$95U2 


JUMP TO **DELAY 


953U- 


FO 


06 




BEQ 


$953C 


BRANCH TO **ROLL 
**ZERO-OUTPUT A LEVEL ZERO 


9536- 


8D 


58 


CO 


STA 


$C058 


TURN OFF 'AN#0' PORT 


9539- 


20 


U2 


95 


JSR 


$951*2 


JUMP TO *DELAY 
**ROLL-INCREMENT TO NEXT BIT 


953C- 


6A 






ROR 




ROLL NEXT BIT INTO THE CARRY BIT 


953D- 


C6 


FD 




DEC 


$FD 


DECREMENT THE COUNTER 


953K- 


DO 


EB 




BNE 


$952C 


LOOP BACK TO **OUTPUT 


95U1- 


60 






RTS 




RETURN 
**DELAY-DELAY FOR 7.U3MS 


95U2- 


A2 


CE 




LDX 


#$CE 


SET COUNTER OF OUTER LOOP 
♦♦OUTER 


95I4U- 


AO 


06 




LDY 


#$06 


SET COUNTER OF INNER LOOP 
♦♦INNER 


95Ub- 


88 






DEY 




DECREMENT INNER LOOP 


95U7- 


DO 


FD 




BNE 


$95U6 


LOOP BACK TO ♦♦INNER f^T"^ 
DECREMENT OUTER LOOP ^M»v__ — ^ 


95U9- 


CA 






DEX 





same case as the last one sent, then a 
shift-up or shift-down character must 
be transmitted. When the most-sig- 
nificant bits are different, the carry 
bit of the 6502 's processor register in- 
dicates in which direction the shift 
should occur. 

After servicing the shift subrou- 
tine, execution moves into the output 
subroutine. The purpose of this sec- 
tion of the program is to change the 
data from a parallel to serial format. 
For this a latched output port is need- 
ed. There are four of these on the Ap- 
ple II, but only one is required. By al- 
ternately setting and clearing annun- 
ciator output O on the game paddle 
connector, a serial bit stream can be 
generated. The timing of each bit 
must be 7.43 milliseconds (ms) long, 
easily done with delay loops. Also, 
each character must be preceded 
with a start bit of logic O and followed 
with a stop bit of logic 1. 

The first step of the output subrou- 
tine is to mask the no longer needed 
MSB to a logic 1 for later use as the 
stop bit. Next, the program clears the 
carry bit of the 6502. This provides 
the needed start bit. The 0, now in the 
carry bit, is transferred to annuncia- 



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Microcomputing, August 1981 99 



Listing 1 continued. 

95UA- DO F8 
95UC- 60 



95UD- 
95UF- 



9551- 
955U- 
9556- 

9558- 
955A- 
955B- 



955D- 
955F- 
9561- 
9563 



9565- 
9566- 
9568- 
95GB 



956C- 
956E' 
957U- 
9572 



957U- 
9575- 
9577- 
957A- 



957B- 

957C 

957F- 



A9 85 
85 FB 



20 1*2 
C6 FB 
DO F9 

A5 FC 
U8 
29 FO 



C9 
FO 
C9 
DO 



68 
29 
20 
60 



C9 
FO 
C9 
DO 



68 
29 
20 
60 



68 
20 
60 



CO 
Ok 
DO 
07 



3F 
FO 



EO 
01* 
FO 
07 



DF 
FO 



95 



FD 



FD 



FO FD 



BNE 
RTS 



LDA 
STA 



JSR 
DEC 
BNE 

LDA 
PHA 
AND 



CMP 
BEQ 
CMP 
BNE 



PLA 
AND 
JSR 
RTS 



CMP 
BEQ 
CMP 
BNE 



PLA 
AND 
JSR 
RTS 



PLA 
JSR 
RTS 



$95l*U 



#$85 
$FB 



$95U2 

$FB 

$9551 

$FC 
#$F0 



#$C0 
$9565 
#$D0 
$956C 



#$3F 
$FDFO 



#$E0 
$9571* 
#$F0 
$957B 



#$DF 
$FDFO 



$FDFO 



LOOP BACK TO 
RETURN 



♦♦OUTER 



♦♦LONG DELAY-FOR CARRIAGE RETURN 
SET COUNTER 
STORE COUNTER IN $FB 

♦♦MACRO 

JUMP TO ♦♦DELAY 
DECREMENT COUNTER 
LOOP BACK TO ♦♦MACRO 

♦♦VIDEO 

RELOAD ORIGINAL ASCII CODE 
SAVE IT ON THE STACK 
MASK OFF BITS 0-3 

♦♦UPPERCASE-ASCII CHARS. $CO-$DF 
IS IT CAPITOL A-0 / ETC.? 
BRANCH TO ♦♦INVERSE 
IS IT CAPITOL P-Z, ETC.? 
BRANCH TO ♦♦LOWERCASE 

♦♦INVERSE-OUTPUT AN INVERSE CHARACTER 
GET CHARACTER FROM STACK 
MASK OFF BITS 6 & 7 
JUMP TO 'COUT1' 
RETURN TO ♦♦RESTORE 

♦♦LOWERCASE-ASCII CHARS. $E0-$FF 
IS IT SMALL A-O, ETC.? 
BRANCH TO ♦♦NORMAL 
IS IT SMALL P-Z, ETC.? 
BRANCH TO ♦♦SAME 

♦♦NORMAL-OUTPUT A NORMAL CHARACTER 
GET CHARACTER FROM STACK 
MASK OUT BIT 5 
JUMP TO 'COUTl' 
RETURN TO ♦♦RESTORE 

♦♦SAME-OUTPUT CHARACTER AS IS 
GET CHARACTER FROM STACK 
JUMP TO 'COUTl' 
RETURN TO ♦♦RESTORE 



tor in the first cycle of the output 
subroutine loop, and is followed by a 
call to the 7.43 ms delay loop. 

Next, the accumulator is right- 
shifted to place the first bit of the 
character code into the carry bit. The 
annunciator output is then set or 
cleared to reflect the value of the car- 
ry bit. Again, the level is held for 7.43 
ms. This cycle continues until all six 
bits of the character code, a seventh 
bit for parity checking, and the logic 1 
MSB as a stop bit are transferred seri- 
ally to the annunciator O port. 

The exact timing of each delay is 
easily adjusted by changing the limits 
of the delay loops. Since the Apple II 
executes about one machine cycle 
per microsecond, the limits were de- 
termined by counting the number of 
machine cycles per loop and dividing 
this number into 7.43 ms. Bear in 
mind that if this were being timed by 
hardware, delicate timing circuits 
would have to be used. Again, be- 
cause software can be easily 
changed, it can be much less trouble. 

Only one more task is left for the 
annunciator port to have all of the 
proper data. That is to provide for an 



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100 Microcomputing, August 1981 



AD & DA CONVERTER 



Z80 MICROCOMPUTER 



6522 APPLE II INTERFACE 



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M 


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J BE one channel A-D & D-A Converter 
can be used with any system having 
parallel ports • Interfaces with JBE 
Parallel I/O Card • D-A conversion 
time — 5 ^s • A-D conversion time — 
20 ^s • Uses JBE 5V power supply 

• Parallel inputs & outputs include 8 
data bits, strobe lines & latches 

• Analog inputs & outputs are medium 
impedance to 5 volt range. _ 



79-287 

Bare Board $39.95 



ASSM. $79.95 
Kit $59.95 



6502 MICROCOMPUTER 






JBE's 4 1 /2x3 1 /4 dedicated controller 
features: • 1024 bytes RAM (two 21 14s) 
• 2048 bytes EPROM (2716) • Uses one 
6522 VIA (comp. doc. fncl.) • Interfaces 
with JBE Solid State Switches & A-D & 
D-A Converter • Uses JBE 5V power 
supply »2716 EPROM available 
separately (2716 can be programmed 
with an Apple II & JBE EPROM Pro- 
grammer & Parallel Interface) • 50 pin 
connector included In kit & assm. 
80-153 ASSM. $110.95 

Bare Board $49.95 Kit $ 89.95 



SOLID STATE SWITCH 




Your computer can control power to 
your printer, lights, stereo & any 
120VAC appliances up to 720 watts (6 
amps at 120VAC). Input 3 to 15VDC 
• 2-14MA TTL compatible • Isolation 
— 1500V • Non zero crossing • Comes 
in 1 or 4 channel version. 



79-282-1 

Bare Board $6.95 

79-282-4 

Bare Board $24.95 



ASSM. $13.95 
Kit $10.95 

ASSM. $49.95 
Kit $39.95 



APPLE II DISPLAY BOARD 




r^flJBtfflBt&sJM 

















JBE's 4-1/8"x3-1/4" single board 
dedicated computer is designed for 
control functions. It features: • A Z80 
Microprocessor software compatible 
with the Z80, 8080 & 8085 
Microprocessors • Uses a Z80 PIO chip 
for I/O which has 2 independent 8 bit 
bidirectional peripheral interface ports 
with handshake & data transfer control 
• Uses one 2716 EPROM (2K) & two 21 14 
RAM memories (1K) • Single 5V power 
supply at 300MA req. • Clock frequency 
Is 2MHz, RC controlled • Board comes 
with complete doc. • 50 pin connector is 
included • 2716 EPROM available 
separately. 

80-280 ASSM. $129.95 

Bare Board $49.95 Kit $1 1 9.95 




PRINTER INTERFACE 




JBE Parallel Printer Interface interfaces your 
Apple II® to Centronics® compatible 
printers. This 3" x 4" board features: on board 
ROM compatible with Integer Basic, 
Applesoft® and Pascal® • Has one 8 bit 
parallel latched output port with selectable 
positive or negative strob e an d one bit input 
selectable for Ready or Ready • Cable and 
Connectors available separately. 

80-297 ASSM. $79.95 

Kit $69.95 
4 ft. Std. Dip Jumpers 16 pin $ 4.25 

Champ Connector "' $ 9.95 



POWER SUPPLIES 



• Use wall transformers for safety 

• Protected against short circuit and 
thermal breakdown. 

5 VOLT POWER SUPPLY 
Rated at 5V 500MA • Operates JBE A-D 
& D-A Converter, Z80 & 6502 Microcom- 
puters, 8085 & 8088 Microcomputers. 

80-160 ASSM. $20.95 

Bare Board $8.95 Kit $16.95 

± 12 VOLT POWER SUPPLY 

Rated at ± 12V 120MA • Can be used as 
a single 24V power supply • Ideally 
suited to OP-AMP experiments. 

80-161 ASSM. $22.95 

Bare Board $8.95 Kit $18.95 



80-144 

Bare Board $25.95 



ASSM. $49.95 
Kit $42.95 



• Has run-stop, single 
step switch • Has 16 
address LEDs, 8 data 
LEDs & 1 RDY LED 

• All lines are buf- 
fered. 



ICS 



6502 $9.95 

6522 $9.95 

Z80CPU $9.95 
Z80 PIO $9.95 
2716 $14.95 
2716 Programmed 




mumiwiiiinut 
• Interfaces printers, synthesizers, 
keyboards, JBE A-D & D-A Converter & 
Solid State Switches • Has handshak- 
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timing • Inputs & outputs are TTL 
compatible. 

79-295 ASSM. $69.95 

Bare Board $39.95 Kit $59.95 



2716 EPROM PROGRAMMER 




JBE 2716 EPROM Pro- 
grammer was designed 
to program 5V 2716 
EPROMS • It can also 
read 2716s. It interfaces 
to the Apple II using 
JBE Parallel I/O Card & 
four ribbon cable con- 
nectors • An LED indicates when 
power is being applied to the EPROM 
• A textool zero insertion force socket 
is used for the EPROM • Comes with 
complete doc. for writing and reading 
in the Apple II or Apple II + • Cables 
available separately. 
80-244 ASSM. $49.95 

Bare Board $24.95 Kit $39.95 

2 Ft. Ribbon Cable $ 4.25 



BARE BOARDS 



APPLE II EXTENDER BOARD 

3Va M x 2 1 /i". Price includes 50 pin Con- 
nector, t 

80-143 $12.95 

8085 3 CHIP SYSTEM 

State-of-the-art system using an 8085, 
8156 & either an 8355 or 8755 

• Instruction set 100% upward com- 
patible with 8080A. 

Bare Board $24.95 

8088 5 CHIP SYSTEM 

An 8086 family microcomputer system 
using an 8088 CPU, 8284, 8155, 8755A 
& an 8185. 
Bare Board $29.95 

CRT CONTROLLER 

This intelligent CRT Controller uses 
an 8085A CPU & an 8275 Integrated 
CRT Controller. It features: • 25 lines 
(80 Char./line) • 5x7 dot matrix • Upper 
& lower case • two 2716s (controller & 
char, generator) • serial interface 
RS232 & TTL • baud rates of 110, 150, 
300, 600, 1200, 2400, 4800 & 9600 

• keyboard scanning system • unen- 
coded keyboard is req'd • uses + 5V & 
± 12V power supplies • Doc. includes 
program listing & composite video cir- 
cuit. 

Bare Board only (Doc. incl.) $39.95 
Programmed 2716s each $19.95 



$19.95 




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Microcomputing, August 1981 101 





Photo 2. The 83-cent circuit before final assembly. The DIP socket was wire- Photo 3. Main circuit board with peripherals connected. Plug game paddles 
wrapped to the pins below and the case glued shut. and the new RS-232C output into game paddle socket (upper right}. 



extra long delay if a carriage return 
character is sent. Another delay loop 
is used to call the 7.43 ms loop several 
times to provide a sufficient pause. 

At this point in the processing, the 
routine could return directly to 
COUT1. However, with a little more 
attention to details, I added a subrou- 
tine to return inverse video charac- 
ters if uppercase letters were printed. 



This is done by masking the normal 
video mode ASCII codes. With lower- 
case letters bits 4-7 were masked to 
allow them to be displayed in normal 
video. The other characters are out- 
put without change. As this is the 
same technique many word proces- 
sor programs employ, it is especially 
convenient for proofreading during 
printout. 



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The program in Listing 1 locates 
the routine at a convenient place in 
memory of a 48K disk system. By set- 
ting the HIMEM limit to just below 
its starting address, it is protected 
from most BASIC applications. 

However, there may be some sys- 
tems in which it would be better to lo- 
cate it at a different address. It is rela- 
tively straightforward to relocate the 
program wherever you want by at- 
tending to the jump-to-subroutine 





RS 232 Standard 




Pin Designation 


I. 


Ground 


2. 


Data (Transmit) 


3. 


Data (Receive) 


4. 


Request to Send 


5. 


Clear to Send 


6. 


Data Set Ready 


7. 


Ground 


8. 


Carrier Detector 


9. 


Data Set Test 


10. 


Data Set Test 


11. 


Unassigned 


12. 


Secondary Carrier Detector 


13. 


Secondary Clear to Send 


14. 


Secondary Data (Transmit) 


15. 


Xmit. Clock (DCE) 


16. 


Secondary Data (Receive) 


17. 


Rcvr. clock (DCE) 


18. 


Unassigned 


19. 


Secondary Request to Send 


20. 


Data Terminal Ready 


21. 


Signal Quality Detector 


22. 


Ring Indicator 


23. 


Data Signal Rate Selector 


24. 


Xmit Clock (DTE) 


25. 


Unassigned 


Table 3. \ 


DB-25 plug. Only pins 3, 5 and 7 are 


used here. 


Perhaps you can figure out a way to 


use the transmit signals so that the terminal 


can transmit as well as receive. 



102 Microcomputing, August 1981 



(JSR) instructions. 

RS-232C Signals from Apple II 

RS-232C signal standards were de- 
signed to supply large enough voltage 
swings that they would not be over- 
come by transmission noise on the 
wire between the sender and the re- 
ceiver. For this reason, voltage levels 
were designed to be from +5 to -h 15 
V for logic level 1 and -5 to - 15 V 
for logic level 0. The only thing that 
the Selectric needs at its input port is 
an RS-232C serial data line and a 
ground reference. What this implies 
is that a simple single-pair speaker 
wire will carry all of the information 
needed. It may be run fairly long dis- 
tances and there is no need for expen- 
sive ribbon cable. 

The annunciator port of the game 
paddle I/O connector can only pro- 
vide a TTL level voltage swing of 0-5 
V. Fortunately, it is a simple task to 
amplify these levels to RS-232C com- 
patible voltages with a one-transistor 
circuit (see Fig. 1). The entire circuit 
consists of only five small parts, so 
with very little effort it can be built 
on top of a 16-pin dual-inline plug 
(DIP). A small cap can then be glued 



over the circuit, leaving only the 
speaker wire running out of it. Any 
time there is a need to disconnect the 
printer, just pull the plug. 

Additionally, it is not too difficult to 
connect another DIP socket onto the 
top of the transistor circuit cap. This 
can carry signals connected in paral- 
lel to the game paddle connector be- 
neath it. That way the game paddles 
may remain plugged in while the 



printer is being used, eliminating 
wear and tear on the plugs. 

The parts for this circuit are cheap 
and easy to find. By using a few junk 
box components and a couple of Ra- 
dio Shack parts, my total costs were 
(yes) exactly 83 cents! I highly recom- 
mend building a test circuit on an ex- 
perimenter's protoboard to check the 
circuit performance before soldering 
it into its case. That will help prevent 



♦ 12V 

(PIN 16, GAME 10) 



6 8K 



27K 



TTL 
(PIN 15, GAME 10) > 
(ANNUNCIATOR #0) 



I00K 
-<vw— — 



C 
Zj J2N390< 



RS-232 
"7 (PIN 3- DB25) 



56 K 



- 12V 

(PIN 9, GAME 10) 



GND >- 
(PIN 8, GAME 10) 



-> GND 

(PIN 7-DB25) 



Fig. 1. TTL-to-RS-232 driver circuit. This one-transistor circuit is the major cost factor in this project! 
Harness it properly and it can also be used to drive modems, high speed printers, synthesizers or any other 
serial input device. 





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26 33/3 pk 



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8 95/ Reload rib. only 
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Microcomputing, August 1981 103 



wasted time if there is a need to de- 
bug the circuit. 

The final part of creating an RS- 
232C port is the easiest to under- 
stand, but it goes against the grain of 
every Apple II owner I know. Don't 
worry! It's really quite minor, but it 
does mean modifying the Apple's 
main board. This is your chance to 
enhance the original design. It is 
nothing that is not already right there 
on the board; it's just not in enough 
places. This modification will im- 
prove your Apple II just by adding 
two small jumpers. The main consid- 
eration before taking this step should 
be the loss of the warranty. If the 
warranty loss is outweighed by your 
improvement, then plunge onward. 

The final step is to run two wires to 
the two unused pins of the game pad- 
dle connector. These provide the 
+ 12 and - 12 V supplies to the tran- 
sistor circuit for the RS-232C voltage 
references. Check the Apple II Refer- 
ence Manual (a great piece of work!) 
and observe that slot 7 has both of the 
needed voltages readily available and 
right next to the paddle connector. 

The first wire should be run from 



pin 33 of slot 7 to pin 9 of the paddle 
connector. The other wire is run from 
pin 50 of slot 7 to pin 16 of the game 
paddle connector. To attach the 
wires, you must get at the back of the 
main circuit board. 

First, turn the Apple II off and re- 
move all cables (line cord, video, cas- 
sette, etc.). Then lift off the lid from 
the Apple II by pulling up sharply at 
the rear of the lid to unsnap the Hed- 
lok fasteners. Set the lid aside. 

Disconnect all plug-in cards (disk 
drive, modem, etc.) and any remain- 
ing video or game connector cables. 

Next, clear a large, clean work sur- 
face and protect it with a pad of some 
sort (e.g., a scrap of rug). Place the 
Apple II upside down upon it. 

Unscrew the four black screws just 
under the front edge of the keyboard 
(see Fig. 2) and carefully set them 
aside. Next, unscrew the two screws 
on the outer edge of the left side, and 
the same on the right side. Unscrew 
the two last screws on each side of 
the back edge. Do not lose these 
screws! 

Now, while tightly holding the top 
and bottom sections together, turn 



the Apple II right-side up. Slowly lift 
up the front edge of the top section 
about two inches. Unplug the key- 
board connector from the main board. 
Lay the top section aside. 

Unplug the power supply by un- 
clipping the metal fasteners. Unplug 
the speaker. 

The main circuit board is attached 
to the bottom section by six nylon 
board supports and one 6/32 nut. 
First unscrew the nut from the center 
of the board. Then, starting at one 
end and working across, unclip the 



' ©1— 






— 1© ' 


9 
i i 






10 

i i 
i i 


5 
© 






7 
© 


6 
© 

■ i 
t-.-i 






8 
© 

a 


© 


2 
© 


3 

© 


© 



Fig. 2. Remove only the screws indicated here. Be 
careful not to separate the top and bottom until the 
keyboard connector is unplugged. 



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104 Microcomputing, August 1981 



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nylon supports by lightly pinching 
them with a small pair of pliers. Be 
sure not to miss the one at location J9. 
The main circuit board should now 
be separated. Remove the main cir- 
cuit board from the base and set the 
base aside. 



BACKSIDE 
OF MAIN 
CIRCUIT BOARD 




33-I2V 



50-H2V 



SLOT 7 



GAME 10 



Fig. 3. Add these two jumpers to the back of your 
Apple's main circuit board to boost its capabilities. 
The most common mistake is to miscount the pins. 



Referring to Fig. 3, connect the new 
wire jumpers to their respective pins 
on the rear of the circuit board. Use 
small #22-#28 gauge solid wire. Do 
not use stranded wire; it tends to 
fray, possibly shorting to other near- 
by pins. 

Measure the distance between the 
pins with a length of wire and cut it 
1/4-inch longer than measured. Strip 
off 1/8-inch of insulation from each 
end. Make a small loop in the stripped 
end of the wire and hook it to the pin. 
Lightly touch a soldering pencil to the 
connection and feed in a minimal 
amount of solder. Avoid using too 
much solder; it could flow across to 
the next pin, causing a short. 

The main problem to watch for at 
this stage is miscounting the pins on 
their respective sockets. Use insulat- 
ed wire and clean soldering tech- 
niques, and you should not have a 
problem. Reassemble everything in 
reverse order. When the power is re- 
applied, check the modification with 
a voltmeter before plugging in the 
transistor circuit. Reversing the sup- 
plies on the transistor could damage 
your unit. 



Once the modification is completed 
and checked, plug in the transistor 
circuit and measure the output volt- 
age level. By slowly toggling the an- 
nunciator port with the BASIC pro- 
gram in Listing 2, voltage swings in 
the 5-15 V range on either side of 
ground should be observed. If not, 
check the wiring and the values of 
the resistors. Also, the parameters of 
different transistors may vary, so try 
substituting a few to obtain the most 
balanced voltage swings. 

The Printer Connection 

Now that everything is done at the 
output end, it is time to prepare the 
Selectric for data input. On the back 
of the Selectric are two points of in- 
terest. The first is the DB-25 plug; the 
other is the line/local switch. Table 3 
shows the pinout designations for the 
DB-25 plug. The idea is to trigger the 
terminal into the receive mode with- 
out having to supply another wire 
from the computer. 

Because of this, only three pins on 
the DB-25 plug have significance in 
this application. Pin 3 receives the 
RS-232C serial data stream from the 



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106 Microcomputing, August 1981 



driver program. Pin 7 is the ground 
reference from the Apple II. And pin 
5 needs to be supplied a logic 1 volt- 
age level to set the terminal in the re- 
ceive mode. 

The logic 1 voltage for pin 5 is sup- 
plied from the 5 V supply within the 
printer. Unsnap the rear cover from 
the printer and locate the terminal 
block on the circuit board within. 
The terminal with the green wire is 
the 5 V supply. The one with the 
black wire is the ground. Measure 
their levels to confirm this. Connect a 



1 


REM 






TOGGLE ANNUNCIATOR 


#0 


10 


POKE - 16296,0: REM - 


• OFF 


20 


GET A$: REM - PAUSE 




30 


POKE - 16295,0: REM - 


• ON 


t*0 


GET A$: REM - PAUSE 




50 


GOTO 10 





Listing2. The SWITCH program is for switch- 
ing annunciator port on and off when testing 
the transistor circuit of Fig. 1. Hit any key on 
the keyboard to toggle the port to the opposite 
state. When the transistor circuit is plugged in, 
its output should swing between + 5 to + 15 V 
and -5 to - 15 V for proper RS-232 operation. 



short wire from the 5 V terminal to 
pin 5 of the DB-25 plug. That is the 
only work needed on the printer. 

Initialization Protocol 

Once the data line is connected to 
the printer and the jumper is in- 
stalled, the interface is finished. It is 
now a working system and ready for 
use. To start it up, there is a short ini- 
tialization protocol that has to be re- 
peated each time the printer is turned 
on. These steps may be performed 
manually, but with some creativity a 
routine could be written to perform 
them automatically. There are five 
steps: 

• Run the printer subroutine in the 
Apple II. 

•Apply power to the printer. 

• Flip the line/local switch to the line 
position. The ready and proceed lights 
on the front of the Selectric will come 
on. 

• Press the initiate key on the right 
side of the Selectric keyboard. The 
proceed light will turn off. 

• Send an EOA code ($B4), which is 
the # character in the EBCD or BCD 
codes or the number 9 in the corre- 



spondence code. 

Once this character is sent, the ter- 
minal is in the receive mode and 
ready to print. 

Added Benefits 

The final result of this project is 
that an RS-232C output port has been 
created at the annunciator pin of 
the game paddle I/O connector. This 
article has harnessed that port for on- 
ly one purpose, but there are others. 
For example, Paul Lutus has included 
a little-talked-about subroutine in his 
excellent word processing program, 
Apple Writer. This subroutine can be 
accessed by entering the word SERI- 
AL in response to the Print Menu. Its 
purpose is to feed a serial-bit stream 
to the annunciator port at one of 
five user-defined baud rates (110, 
150, 300, 600 and 1200 bits per sec- 
ond). 

There is no reason that the transis- 
tor circuit described in this article 
cannot be harnessed to output this 
ASCII coded information just as easi- 
ly as it outputs the data streams cod- 
ed for Selectrics. The ramifications of 
this are that high-speed serial input 




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Microcomputing, August 1981 107 



devices can also be connected for just 
83 cents! In fact, this is the only way 
that Apple Writer can take full ad- 
vantage of some printers. 

Don't feel that the modification I 
have described here is limited to just 
printers— try plotters, modems, syn- 
thesizers or any other device that 
needs to receive RS-232C serial data 
from the Apple II. 

The Reality of It All 

The Selectric I purchased is a Car- 
terfone S15B Data Terminal, which 
CFR Associates advertises for under 
$500. It comes as is, which translates 
to: "it works, with quirks." Mine had 
a broken paddle on the line/local 
switch and I had to add a power cord. 
The folks at CFR (Box 144, Newton, 
NH 03858) have been helpful to me 
on the phone, and have been able to 
provide technical assistance in the 
form of a very lengthy manual about 
I/O electronics. 

After several months of heavy use, 
the Selectric has earned its keep. So 
far it has not needed any repairs, but 
the good tend to die young, so it 
would probably be worth obtaining a 



repair manual to keep everything 
running smoothly. It is also a good 
idea to acquaint oneself with the local 
Selectric service personnel. They can 
supply new ribbons (even fancy car- 
bon ribbons), type elements and an- 
swers to technical questions about 
the machine. Most advertise in the 
phone book. 

One of the advantages of Selectrics 
is that they have a friction-feed platen. 
Individual sheets of paper or inexpen- 
sive newsprint paper rolls may be 
used. A good source of roll paper is the 
local radio station. They are provided 
reams of it from their newswire ser- 
vices and can usually part with sever- 
al cases at a time (for free!). A modi- 
fied toilet paper dispenser is just fine 
for holding the roll and centering it so 
that it does not "walk" back and forth 
on the carriage. And, if it is really 
needed, pin-feed platens may be pur- 
chased from service centers, giving 
you the best of both methods. 

Conclusion 

When I set out to build this inter- 
face, the primary motive was money. 
Now that I have had time to look 



back on it all, I realize that an even 
larger incentive was to expand the 
versatility of the Apple II via a grass- 
roots effort. This microcomputer is 
tops in its class not just because of its 
design, but because owners and users 
have made imaginative use of its 
abilities. 

If its users get too dependent on 
manufacturers to provide all of the 
expansion, the Apple II will quickly 
become outdated. On the other hand, 
as long as the users remain skilled in 
their craft, the Apple II will continue 
to dominate the market. Building this 
letter-quality printer interface makes 
investment in an Apple II the best 
choice you ever made.B 

References 

1. "ASCII-to-Selectric Software 
Driver,' Robert Munn, Kilobaud Mi- 
crocomputing, Nov. 1979, p. 134. 

2. "Programming the 6502," Rodney 
Zaks, SYBEX, Inc., 1979. 

3. "6502 Applications Book," Rod- 
ney Zaks, SYBEX, Inc., 1979. 

4. 'Microcomputer Interfacing,' 
Bruce A. Artwick, Prentice Hall, Inc., 
1980. 



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108 Microcomputing, August 1981 



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Microcomputing, August 1981 109 



Don't be a slob, be "pretty" when it comes to formatting BASIC listings. 



Apple BASIC 
Prettyprinter 



Many high-level languages avail- 
able under large operating sys- 
tems (e.g., Pascal, C or LISP) have ac- 
cess to a prettyprinting program to 
automatically reformat other pro- 
grams in a specified way to render 



10 


REM PROGRAM TO FIND ALL 


13 


REM PERFECT NUMBERS<N 


20 


TEXT : CALL -936: VTAB 10: INPUT 




"WHAT VALUE OF N"»N 


30 


DIM PN(IO): NUMPERF=1 PN<1>- 

1 

REM MAIN LOOP 


40 


50 


FOR NUM=2 TO N. SUM=0 


60 


FOR DIV=1 TO NUM-1: IF NUM MOD 




DIV=0 THEN SUM»SUM+DIV: NEXT 




DIV 


70 


IF SUM#NUM THEN 90 


80 


NUMPERF =NUMPERF+ 1 . PN ( NUMPERF ) 




»NUM 


90 


NEXT NUM 


100 


REM PRINT NUMBERS 


110 


FOR 1=1 TO NUMPERF: PRINT PN( 




I), NEXT I 


120 


END 


Sample la. Sample Integer BASIC program. 



10 REM PROGRAM TO FIND ALL 
15 REM PERFECT NUMBERS<N 

20 TEXT : 

CALL -936: 

VTAB 10: 

INPUT "WHAT VALUE OF N'\ N 
30 DIM PNC 10): 

NUMPERF=i: 

PN(1)-1 

40 REM MAIN LOOP 

50 FOR NUM«2 TO N: 

SUM=0 
60 FOR DIV=1 TO NUM-1: 
IF NUM MOD DIV«0 

THEN 
SUM«=SUM+DIV: 
NEXT DIV 
70 IF SUM#NUM 
THEN 
90 
80 NUMPERF=NUMPERF+1: 

PN ( NUMPERF ) =NUM 
90 NEXT NUM 



100 REM PRINT NUMBERS 



110 FOR 1=1 TO NUMPERF 
PRINT PNC I). : 
NEXT I 
120 END 



Sample lb. Program in Sample la after pretty- 
printing. 



By Michael Keith 

them more readable and understand- 
able. 

This simple prettyprinter, written 
in BASIC, is for the Apple II. It uses 
the powerful disk operating system 
file commands to manipulate the BA- 
SIC source program into a form suit- 
able for prettyprinting. The system ac- 
cepts programs written in either type 
of Apple BASIC (Integer or Applesoft). 
You can use this prettyprinter for 
final documentation of your own pro- 
grams or as a study tool for reading 
programs written by others. 

A Description 

First, you read your program into 
memory. Next, a short program is ap- 
pended to the end and run. This pro- 
gram transfers your program into a 
text file on disk. You then run the 
main program, which reads in the 
text file and processes it to produce 
the prettyprinted output. 

The features of the prettyprinter 
output include highlighting of groups 
of one or more REM statements, au- 
tomatic breakup of multiple-state- 
ment lines and FOR-NEXT and IF- 
THEN indentation. 

A sample program and the output 
generated by the prettyprinter are 
shown in Sample 1. 



30000 D$»" "|REM CTRL-D 


30005 PRINT D$;"0PEN LISTING" : PRINT D$; 
"DELETE LISTING" 


30010 PRINT D$;"0PEN LISTING" : PRINT D$; 
•WRITE LISTING" 


30020 POKE 33. 30 J LIST 1,30000 


30030 PRINT D$; "CLOSE LISTING" 


300M) END 


RUN 30000 


RUN PRINT 


Listing 1. Contents of the text file APPRINT. 



The prettyprinter program consists 
of two files, which must reside on the 
same diskette: a text file called AP- 
PRINT and an Applesoft program 
called PRINT. The contents of AP- 
PRINT are shown in Listing 1. This 
text file can be created by writing a 
short program which opens a file 
called APPRINT, prints these lines 
and closes the file (for a detailed de- 
scription of text files, see the Apple 
DOS manual). To operate the pretty- 
printer, do the following: 

1. Load the BASIC program you 
wish to prettyprint into memory. 

2. Insert the diskette containing 
the prettyprint files and type EXEC 
APPRINT. 

After doing this, the following se- 
quence of events takes place: 

1. The program lines in APPRINT 
are appended to the user program. 

2. The RUN 30000 command puts 
the user program in a text file called 
LISTING. 

3. The main program, PRINT, is 
executed. 

The main program, PRINT, is giv- 
en in Listing 2, which was produced 
by the prettyprinter itself as a sample 
of its output. 

The most time-consuming section 
of the PRINT program is the initial 
reading in and preprocessing of the 
program (lines 1-65). This can take 
from half a minute to five minutes de- 
pending on the size of the program. 
During this stage, the program is sep- 
arated into single statements, which 
are stored in array elements A$(l), 
A$(2) . . . A$(N). The user is then pre- 
sented with a menu of functions: P 
for prettyprint, I for index or Q for 
quit. 



Address correspondence to Michael Keith, D46 
Abbington Drive, Hightstown, NJ 08520. 



110 Microcomputing, August 1981 



CompuServe is 
a lot more than 
fun and games 
and news. 



Although we're probably best 
known for our consumer-oriented 
services, CompuServe maintains 
powerful services for the serious 
computer user. CompuServe has 
helped some of the nation's largest 
companies and financial institu- 
tions through a wide range of 
business and scientific-oriented 
computer programs. With our 
Information Service, we can extend 
this expertise to you. Here are 
some of the programs available 
to the personal computer user 
through the CompuServe 
Information Service: 

PASCAL: DEC User Group 

version of this famous language. 

XF4: Extended CompuServe 

Fortran compiler. 

MACRO: Advanced Macro 

Assembly language for PDP-10. 

Talk about fast. 

FILGE: Fast, easy file generator 

and editor. Line oriented, no line 

numbers required! 

XBASIC: CompuServe extended 

BASIC. 

JUMBLE: File encryption program. 

TECO: High level text editor. 

LINK: Linking loader program. 

DDT: Dynamic debugging tool. 



CREF: Symbolic cross-reference 
generator used with language 
compilers. 

FILCOM: File comparison 
program. 

SALARY: Calculates salary and 
increases in various time frames 
including per year, month, period 
and hour. This program is intended 
primarily for managers doing 
reviews. 

SNOBOL: String manipulation 
language. 

RUNFLO: Text formatting 
program (write resumes etc.). 
RUNF10: Word processing and 
text formatting program (write 
resumes etc.). 
CONCOR: Concordance 
generator. This program is very 
useful for documentation purposes. 
CONCOR reads an ASCII file and 
creates an output file which con- 
tains a line numbered listing of 
the original file, and a list of all the 
words contained in the file along 
with the numbers of the lines on 
which each word occurs (similar 
to an index). 

B LIS 10: High level implemen- 
tation language for DEC PDP-10. 
BINED: Binary file editor. 
APL: A Programming Language. 



FINTOL: Financial analysis tool. 
Contains several program modules 
which can perform financial analy- 
sis for business or personal needs. 
— Loan Payment and Amortization 
— Compound interest Calculations 
— Sum from a Periodic Investment 
— Sinking Fund Deposit 
— Present Value of Cash Flows 
— Present Value and Internal Rate 

of Return (Capital Projects) 
— Depreciation Analysis 
— Compound Growth Rates 
RANNO: Random number 
generator. 
XEDIT: XF4 binary file editor. 

We also offer high speed 
professional line printer service, 
error-free file transfer, 
CompuServe's Software 
Exchange, and computer 
manufacturers' newsletters. 
Computer Users Groups can 
exchange information and 
up-to-the-minute gossip in the 
computer world. 

And ... if Aunt Matilda comes 
over, you can still let her play 
Adventure. Demonstrations and 
software at all Radio Shack® 
Computer Centers and many 
Radio Shack® outlets. 




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(614)457-8600 



Radio Shack is a trademark of Tandy Corporation. 



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As listed in Listing 2, the pretty- 
print option (P) will cause a hard- 
copy printout through an interface 
card in slot 2. To change to a different 
slot, merely change line 1001. To 
prettyprint to the video display only 
(the mode I usually use the program 
in), merely delete line 1001. In this 
mode, pressing any key on the key- 
board can be used to pause and re- 
sume the listing at any point. The in- 
dex option (I) produces a list of all 
REM statements in the program on 
the CRT. This is useful for locating a 
specific routine or for reading a pro- 
gram's documentation. 

The formatting rules used by the 
prettyprinter follow: 

1. A block of REM statements is 
highlighted as follows: 

(blank line) 

*************** 

(REM statements) 



Exception: In a multiple-statement 
line whose first statement is not a 
REM, the blank line and the asterisks 
are suppressed. 

2. FOR-NEXT loops are indented 
as follows: 

FOR (expression) 

i ) 

( statements ) 

( ) 

NEXT 

Loops within loops are indented fur- 
ther (once for each increase in nesting 
depth). 

3. IF-THEN statements are refor- 
matted as follows: 

IF (expression) 
THEN 

statements 

Finally, note that a prettyprinted pro- 
gram is not executable BASIC. How- 
ever, it is simple to reconvert a 
prettyprinted listing to legal BASIC. 
You merely delete the REM high- 
lighting, group the multiple state- 
ments together and then write IF- 
THENs on one line. 

Summary 

I have described a simple pretty- 
printer for Apple II BASIC programs, 
but there are many possible enhance- 
ments. One of the most useful (and 
also one of the most difficult) en- 
hancements is to recode parts of the 
program in machine language for in- 
creased speed. Nevertheless, the pro- 
gram presented here has proven a 
useful tool for better understanding 
of programs and their operation. The 
basic technique of capturing and ma- 
nipulating a BASIC program as a text 



file can be used to produce more 
elaborate prettyprinters, conversion 
programs (e.g., to convert from one 
type of BASIC to another) or fancy 
program editors. These and other 
possibilities are left to you for further 
experimentation. ■ 



Listing 2. PRINT, the main pretty printing 
program. 

1 TEXT 

DIM A* (500) 



3 


REM READ IN PROGRAM FROM FILE 'L 




ISTING- 


4 


REM AND BREAK INTO SINGLE STATEM 




ENTS 



8 
10 



20 
21 



23 



25 



27 



30 
40 



50 
60 



62 
65 
67 



N = 1: 

D* = CHR* (4). 

PRINT D*i "OPEN LISTING": 

PRINT DS; "READ LISTING" 

As(0) = "": 

C ■ 

HOME : 

VTAB 10: 

PRINT "PROGRAM IS BEING READ IN A 

ND PROCESSED. " 

GET A* 

IF AS = CHRS (13) AND LEN (As(N 

) ) =» 

THEN 
20 
IF A* = CHRS ( 13) 

THEN 
N « N ♦ 1. 
As(N) = "": 
C = 0: 
GOTO 50 
IF AS = CHRS (34) 

THEN 
C « C ♦ 1 

IF AS = ": " AND INT (C / 2) » C 
/ 2 

THEN 
A*(N) = AS(N) ♦ AS: 
N • N ♦ i: 
A»(N) = "": 
C = 
GOTO 50 

As(N) = A*(N> ♦ AS 
IF A*(N) = "30000" 

THEN 
60 

GOTO 20 

PRINT DSi "NOMON": 
VTAB PEEK (37): 
CALL - 868 
N ■ N - 1 
PRINT DSi "CLOSE LISTING" 



68 


REM INITIAL FORMATTING 


70 
72 


GOSUB 2000 


75 


REM NOW GO TO MAIN MENU 



80 


GOTO 500 


95 




*************************************** 


96 


REM A COLLECTION OF SUBROUTINES 


97 


REM PLACED HERE FOR SPEED 


100 


REM REM-CHECK 


101 


BFLAG = 0: 




EFLAG = 


102 


IF MIDS (ZS. 7.3) < > "REM" 




THEN 




RETURN 


no 


IF MIDS (ZS, 11. 1) < > " " 




THEN 




ZS = LEFTS (ZS, 9) ♦ ■ • ♦ RIGHT 




* (Z*. LEN (Zs) - 9) 


120 


IF MIDs <A*(I - 1),7,3) < > "RE 




M" AND LEFTS (Z»,6) < > " 




THEN 




BFLAG = 1 


130 


IF MIDS (As(I + l).7t3> < > "RE 




M" 




THEN 




EFLAG = 1 


139 


IF BFLAG = 1 




THEN 




PRINT 


140 


IF BFLAG = 1 




THEN 




PRINT "*#*«•**«***♦**«♦»*♦***♦»* 



190 
199 

200 



RETURN 



REM IF-THEN CHECK AND PRINT 




More 



112 Microcomputing, August 1981 



Listing 2 continued 



210 IF MID* (Z*. 7. 2) < > "IF" 
THEN 
RETURN 
220 L* = Z* 
230 FOR J » 9 TO LEN ( Z$ ) 

IF MID* (Z*, J, 4) = " 
THEN 
THEN 250 
240 NEXT J 
250 Z* = LEFT* (L*. J - 1): 

GOSUB 405 
260 PRINT SPC < TB + 6 + 3); "THEN" 
270 Z* = " " + RIGHT* (L*. LEN 
(L*) - 4 - J): 
CttSUfe *tf5 
275 IF MID* <L*. J + 6,3) = "FOR" OR 
MID* (L*..J + 5,3) - "FOR" 
THEN 
TB = TB ♦ 3 
280 POP 

RETURN 
399 



400 


REM FOLD AND 


PRINT Z* 


402 


GOSUB 100 
REM CHECK IF 


REM 


403 


GOSUB 200 
REM CHECK IF 


IF-THEN 



405 


IF LEN <Z*> < 39 - TB 
THEN 






PRINT LEFT* (Z*, 6), SPC ( TB ) 


R 




IGHT* (Z*, LEN <Z*> - 6): 






GOTO 447 




410 


PRINT LEFT* (Z*, 6), SPC ( TB). 
D* (Z*. 7, 39 - TB - 6) 
X = 40 - TB 


MI 


420 


L • X ♦ 32 - TB 

IF L > LEN <Z*) 

THEN 
L = LEN <Z*> 




425 


PRINT SPC( TB ♦ 6); 




430 


PRINT MID* (Z*, X.L - X ♦ 1) 




440 


IF L = LEN (Z*) 

THEN 
447 




445 


X = X ♦ 33 - TB 
GOTO 420 




447 


IF EFLAG = 1 
THEN 

DD T KIT ■• — — — j__i 






mm n 




448 


RETURN 





44v 



5O0 



REM MAIN MENU 



P - PRINT PROGRAM' 
Q - QUIT" 



510 HOME : 

VTAB 3: 

PRINT " **» APPLE BASIC PRETTYP 

RINTER »«»" 
520 VTAB 8: 

PRINT " I - INDEX TO ALL REM ST 

ATEMENTS" 
550 PRINT . 

PRINT " 
565 PRINT : 

PRINT " 
580 VTAB 22 

PRINT : 

GET A* 
585 IF A* - "Q" 
THEN 
END 

590 IF A* = "P" 

THEN 
GOSUB 1000 
GOTO 500 

591 IF A* » "I" 

THEN 
GOSUB 1800 
GOTO 500 
599 GOTO 580 
999 



1000 


REM 


PAGE LIST 


1001 


PR* 


2 


V002 


TB 


=• 




REP 


INITIALIZE TAB 


1005 


HOME 


1010 


FOF 


1 I ■ 1 TO N 

Z* ■ A*( I ) 
GOSUB 400 


1030 




IF PEEK ( - 16384) > 127 
THEN 
POKE - 16368,0 
GET A* 


1040 




REM CHECK FOR NEW TAB (FOR OR 
NEXT) 



1055 IF MID* (A*(I),7,3) ■ "FOR' 
THEN 
TB « TB + 3 
1080 IF MID* (A*(I ♦ 1),7,4) < 
"NEXT" 

THEN 
1089 



1085 


COUNT = 1: 




FOR Q = 5 TO LEN (A* (I + 1)) 


1 036 


IF MID* (A*(I + 1), Q, 1) = 

II II 




J 

THEN 




COUNT = COUNT + 1 


1087 


NEXT Q 


1088 


TB = TB - 3 * COUNT 


1089 


NEXT I: 




PRINT 


1090 


VTAB 24 




PRINT "PRESS ANY KEY FOR MAIN MEN 




U . . . "i : 




GET A*: 




RETURN 


1100 


END 


1799 




*************************************** 


1800 


REM REM- INDEX 


1810 


HOME 




VTAB 2: 




PRINT " ###### REMARK INDEX * 




#«### 


1820 


PRINT : 




FOR I = 1 TO N 



1825 



IF MID* (A*(I),7,3) < > "REM 



THEN 
1900 
1828 T = 10 

1830 IF MID* (A*(I),T, 1) = " " 
THEN 
T ■ T + 1: 
GOTO 1830 
1835 Z* = LEFT* (A*<I),6) + " " + 
RIGHT* (A*(I), LEN <A*(I)> - 
T + 1) 
1838 GOSUB 400 
1840 IF PEEK (37) < 21 
THEN 
1900 
1850 VTAB 24. 

PRINT " PRESS RETURN FOR MORE 
, ESC TO QUIT "; 
1860 GET A*: 

IF ASC (A*) = 27 
THEN 
RETURN 
1870 HOME 
1900 NEXT I 
1910 VTAB 23: 

PRINT "PRESS ANY KEY FOR MAIN MEN 
U. . . " : 
GET A*: 
RETURN 

2000 REM INITIAL FORMATTING 

2001 REM LEFT- JUSTIFIES LINE NUMBERS 
AND ALIGNS STATEMENT BEGINNINGS 

2002 IF LEFT* (A*(l),l) ■ " " 

THEN 
TYP = 1. 
REM TYP=1 MEANS INTEGER BASIC 

2005 FOR I = 1 TO N 

2010 A = ASC ( LEFT* (A*(I),1)> - 
ASC ("0") 

2012 IF TYP = 

THEN 
2020 

2013 K ■ 1 

2014 IF MID* (At(I).K. 1) « " " 

THEN 
K « K ♦ 1: 
GOTO 2014 

2015 A = ASC ( MID* (A*(I).K. 1)) - 

ASC ("0") 

2016 IF A < O OR A > 9 

THEN 
2100 

2017 GOTO 2200 

2020 IF A < O OR A > 9 
THEN 
2100 
2030 J ■ 1 

2040 A = ASC ( MID* ( A*( I ) , J, 1 ) ) : 
A = A - 128 » INT (A / 128). 
IF (A > 47 AND A < 58) OR A = 
32 

THEN 
J - J + 1: 
GOTO 2040 
IF J > 6 

THEN 
2200 
FOR K = J TO 6: 

A*(I) = LEFT* (A*(I),J - 1 
) ♦ " " + RIGHT* (A*(I), L 
EN (A*( I ) ) - J + 1 ) : 
NEXT 

GOTO 2200 
J = 1 

A = ASC ( MID* (A*(I), J, 1) ): 
IF A = 32 

THEN 
J = J + 1. 
GOTO 2110 
2120 A*(I) ■ « " + RIGHT* (A* 

(I), LEN (A*(I) ) - J + 1) 
2200 NEXT I: 

X = FRE (0) 
RETURN 



2045 



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Factory warrantees on Apple and 
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carry Computer Plus 180 day war- 
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**See List of Advertisers on page 194 



Microcomputing, August 1981 113 




ENGINEERING AND PRODUCTION CONTROL SYSTEMS 



< 
O 

o. 

Q. 

< 









Company founder and president, Walter L. Myers 
(right), pictured with production engineer Joe 
Zellers who developed the production control 
software for the MSI computer system. 

system. Since 1975, the MSI system has been 
expanded to accommodate four users 
simultaneously, performing a variety of plant 
monitoring functions and management 
programs." 

"The system is equipped with 10 megabytes of 
hard disk storage presently and we plan to add an 
additional 10 megabytes of storage soon. The 
maximum downtime has been only one or two 
days in the 5 years that the system has been in 
operation. MSI has provided excellent technical 
support and willingness to help us with our 
special requirements. We have nothing but 
praise for MSI, they have provided excellent 
system support." 

SPRING ENGINEERING AND DESIGN 

"All of the production at Myers Spring is 
performed to exact customer specifications 
rather than to the manufacture of standard spring 
products. This causes an ever increasing 
demand for quick and efficient design and 
engineering capabilities. Many parameters have 
to be taken into consideration in the design of 
any particular spring, including wire size, wire 
type, material modulus, spring diameter, number 




One of four workstations where design 
engineering, checking of sales order status, and 
production control monitoring is performed. 



THE COMPANY: 

MYERS SPRING COMPANY, INC. 
LOGANSPORT, INDIANA 

Myers Spring Company, Inc. was founded 35 
years ago by Walter L. Myers for the manufacture 
of small mechanical springs which are used 
widely in mechanical appliances, electrical 
equipment, and by the automotive, construction, 
and many other industries. The Myers Spring 
company has grown to several million dollars in 
annual sales and employs approximately 50 
people in its production facility. 
Production engineer Joe Zellers comments, "we 
began looking at computer systems 
approximately ten years ago in order to keep up 
with the increasing demand of order processing, 
custom mechanical spring design engineering, 
and production control. In 1975, we selected the 
MSI system because they were the first company 
in the microcomputer industry to offer the 
necessary peripherals which would convert a 
microcomputer system into a usable business 




The production facility at Myers Spring Co. is 
equipped with many automated machines for 
mechanical spring production. 

of turns per inch, free length, spring loading, rate, 
solid height, working stress, working 
temperature, number of operating cycles, 
hysteresis, resonant frequency, expansion, and 
whether the spring has to be ground or not. It 
used to take over an hour for an engineer to 
design a spring taking into account all of these 
parameters. However, with the engineering 
software which we have developed for the MSI 
system, spring design can be completed in less 
than one minute by simply keying in the desired 
parameters. The MSI computer system not only 
designs the spring for us but prepares a complete 
quotation for the customer after consideration of 
the material to be used, the amount of waste, 
which equipment the production will use, the 
speed of the machines, the necessary labor rate, 
as well as the desired percentage of profit." 



114 Microcomputing, August 1981 



SALES QUOTATION SYSTEM 

Following the computer spring design procedure, with automatic quotation feature, the actual 
production begins. Each quotation is reviewed and compared to actual job cost reports on the 
production run in order to make any necessary refinements in the quotation system software This 
feature of our system has greatly improved our ability to prepare accurate quotations and to insure 
profitability of the company. 

PRODUCTION CONTROL/JOB COST ACCOUNTING 

Each production work order is tracked by the computer system at each stage of the production process 
First, each order is checked against the customer quotation for accuracy. As each order is processed 
exact shop labor time is recorded, for each production machine used, and each stage of the production 
process. Summary reports are produced showing the total amount of material used, time used on each 
production machine, amount of material used, and a total cost figure for each work order 
SALES SUMMARY REPORTS 

The system is designed to produce monthly sales summaries which show the amount of products sold by 
each salesman, complete with dates, order numbers, type of product, quantity, type of material material 
cost, sales commissions, etc. Totals for each desired category and for each salesman are reproduced 
ACCOUNTS RECEIVABLE SYSTEM 

Each morning, invoices are generated for orders which will be shipped that day The accounts 
receivable system maintains accounts for over 500 active customers. The system produces monthly 
statements complete with aging of open invoices. 
MULTI USER CAPABILITY 

The MSI system is equipped with four user 
terminals presently which are available for use 
simultaneously by the following departments: 
Order department, for entering new orders and 
checking order status. Inventory department, 
used for checking to see whether a particular 
product has been produced previously. 
Invoicing/Cost Accounting, used for preparation 
of invoices and for entry of labor and material 
cost accounting information. Design 
Engineering, used by company engineers to 
design new products. 



Order entry, invoicing, monthly statements, and 
other management reports are carried out at this 
workstation at Myers Spring Co. 

GENERAL LEDGER TIE-INS 

The MSI system automatically prepares journals for cost 
accounting information and sales data which can then be 
posted to the general ledger. Complete income statements and 
balance sheets are produced by the general ledger programs on 
the system. 

MULTIPLE MANAGEMENT REPORTS 

The MSI system is used in many different areas of the company 
in order to provide more efficient and effective management of 
our production facilities. Several of the reports which we obtain 
from the system are: production schedules, due list for orders, 
new orders list, production summary by department, 
salesman's reports, individual customer reports and order 
histories, time studies, sales quotations, design engineering, 
sales summaries, customer statements, general ledger balance 
sheet and income statements. 

Consider MSI, evaluate us, talk to our users, and we think you'll 
buy your business system from us! 

If you would like to know how an MSI business system can help 
you make your business more profitable, call or write, 
MIDWEST SCIENTIFIC INSTRUMENTS, INC., 220 W. Cedar, 
Olathe, KS 66061, 800-255-6638, Telex 42525 or 437049 





The MSI system at Myers Spring 
Company is equipped with 10 
megabytes of hard disk memory, dual 
floppy disk drives, a high speed 
printer, and four user CRT terminal 
workstations. 




MSI Helping to make your business run better. 




*^144 



^See List of Advertisers on page 194 



Microcomputing, August 1981 115 




This article, along with recent developments in single-chip clock circuit design, simplifies the task of 

adding timekeeping ability to your Apple. 




Time 



thelApple 



By David Goss 



Computerists often find it useful to 
keep track of time. To fill this 
need you can buy Apple's ready-to- 
plug-in Clock/Calendar Card for 
around $280. Or, you might want to 
construct a versatile real-time clock/ 
timer circuit card that will cost you 
only $50 to $60. It is designed for the 
Apple, but can be adapted to other 
systems by modifying the bus inter- 
face. 

Our needs for timekeeping in com- 
puting generally fall into one of two 
categories. The first is interval tim- 
ing; i.e., controlling or measuring the 
duration of an event, or the time be- 
tween events. For example, comput- 
er-generated music and other sounds 
can be created by timing the interval 
between speaker pulses to determine 
pitch, and by timing the duration of 
each tone. You can do this with in- 
struction loops, but using a hardware 
timer provides much greater accura- 
cy and resolution, and does not re- 
quire experimenting or cycle-count- 
ing to derive the number of instruc- 
tions necessary for a desired time in- 
terval. 

The second category involves the 
time-of-day and/or the date. Your 
computer might need a clock, for ex- 
ample, to determine when to turn 
lights or appliances in your comput- 
er-controlled home on or off, or to ac- 
tivate your modem to get the opening 
stock market reports while you catch 
an extra 40 winks. Functions of this 
sort are easily implemented with the 
help of a hardware clock. 

You can make your timing device 
more useful by giving it the ability to 
generate interrupts to the processor. 
You can then set up a desired time 
function and put the processor to 
work doing other things until the in- 
terrupt occurs to indicate that the 



function is complete, rather than hav- 
ing to continuously monitor time. 

Thanks to large-scale integrated 
circuits, you can make a clock, calen- 
dar, timer and interrupt processor 
with just two large-scale integration 
(LSI) circuits, to provide the follow- 
ing features: 

•Time in hours, minutes and sec- 
onds 

• 12- or 24-hour format 
•Date in month, day and year 

• Day of the week 

• Programmable interrupts once 
every second, minute or hour 
•Two programmable interval timers 

• Battery operation while the com- 
puter is turned off 

The LSI circuits are the OKI 
MSM5832 real-time clock/calendar 
and the 6522 versatile interface 
adapter. 

Clock/Calendar 

The MSM5832 is an 18-pin CMOS 
IC which provides the full range of 
clock/calendar functions. It features 
an on-chip 32,768 Hz crystal-con- 
trolled time base, which is counted 
down to provide addressable four-bit 
binary-coded decimal (BCD) data de- 
scribing hours, minutes, seconds, 
year, month, date and day of week. 
Data access is controlled by a four-bit 
address and by chip select, read and 
write inputs. Table 1 shows the ad- 
dress selection codes. A hold input is 
also provided to prevent the internal 
registers from being counted down 
during read or write operations. Tim- 
ing accuracy will not be affected by 
the hold input if it is active for less 
than one second at a time. 

The circuit also provides pulse out- 
puts at rates of 1024 Hz, once/second, 
once/minute and once/hour on the 
data lines under the conditions speci- 



fied in Table 2. I'll describe the use of 
these outputs to generate interrupts 
later. 

The clock may be programmed to 
operate in either 12- or 24-hour for- 
mat. In the 12-hour format it provides 
an AM/PM indicator. The calendar will 
roll over correctly for 30-day and 
31 -day months, and can adjust for 
leap years. The latter requires that 
the leap year bit in register 8 be set 
prior to midnight of Feb. 28 in the 
leap year. The clock will count a 29th 
day in February, and will automati- 
cally reset to give 28-day counts in 
succeeding Februarys. The leap year 
bit thus requires setting once every 
four years. 

The MSM5832 is too slow to inter- 
face directly with the Apple bus. The 
hold input, for example, must be ac- 
tive for a minimum of 150 us prior to 
a read or write, and address inputs 
must be stable for at least six us prior 
to a read. An interface buffer is there- 
fore necessary. 

Versatile Interface Adapter 

I selected the 6522 as the bus inter- 
face device primarily for its timer 
and interrupt ability. A block dia- 
gram of the device is shown in Fig. 1. 
Its full capability is too extensive to 
describe here, but I will cover the 
major points of interest. 

The 6522 provides two bidirection- 
al eight-bit I/O ports, e^cVv l\re. oi 
which can be independently pro- 
grammed by the corresponding data 
direction register to act as either an 
input or an output. There are also two 



David Goss (2021 Kornat Drive, Costa Mesa, CA 
92626) is an electronics engineer employed in the 
aerospace industry. He has been an Apple user for 
a year and a half, and enjoys both hardware and 
software design. 



116 Microcomputing, August 1981 



control lines associated with each 
port, with each control line (CA1, 
CA2, CB1, CB2) programmable via 
the peripheral control register as 
either an interrupt input or an out- 
put. The port B control lines can also 
be used as a serial port to/from the 
shift register. 

There are two on-chip 16-bit timers 
whose operating modes are con- 
trolled by the auxiliary control regis- 
ter. Both timers operate by counting 
down from a preset value and set in- 
terrupt flags when the count reaches 
zero. Timer Tl counts down on the 
1-MHz-system clock, and so can time 
intervals of from one to 65,535 us. It 
can operate in either a one-shot or 
free-running (repeating) mode. 

Countdown values are stored in 
two eight-bit latches. In the free-run- 
ning mode, the contents of these 
latches are automatically transferred 
to the counter each time the count 
reaches zero. The latches can be load- 
ed while the timer is counting, thus 
letting you modify the timing interval 
"on the fly." 

Timer T2 can be used as a second 
one-to-65,535 us interval timer, or 
can be programmed to count down 
on pulses applied to line 6 of port B. 
That feature is used in this clock cir- 
cuit to count on the 1024 Hz output 
from the clock chip, thus giving a tim- 
ing range of (approximately) one to 
65,535 ms. 

The 6522 can handle seven sepa- 
rate interrupts, one each from CA1, 
CA2, CB1, CB2, Tl, T2 and the shift 
register. Each interrupt has a corre- 
sponding bit in each of two registers, 
the interrupt enable register and the 
interrupt flag register. The interrupts 
may be selectively enabled or dis- 
abled by setting the appropriate bits 
in the IER to 1 or 0, respectively. 

When an interrupt condition is 
met, a specified flag bit in the IFR is 
set. Bit 7 of the IFR is also set when 
any of the flag bits are set. If a flagged 
interrupt is enabled, the 6522 will 
lower the interrupt request (IRQ) 



Address 


Internal 
Counter 


Data 


Data 
Range 




A 3 


A 2 


A, 


A 


dJ 


D 2 


D, 


Do 














sec lo 










0-9 


Set to zero regardless of input 
when written to 











1 


sec hi 


* 








0-5 








1 





min lo 










0-9 










1 


1 


min hi 


• 








0-5 







1 








hrlo 










0-9 







1 





1 


hrhi 


A 


▲ 






0-1 
0-2 


D 2 = 1 for PM D 3 = 1 for 24 hr 
D 2 =0for AM D, = 0for 12 hr 





1 


1 





day of wk 


* 








0-6 







1 


1 


1 


day lo 










0-9 




1 











day hi 


* 


A 






0-3 


D 2 = 1 for 29 days in Feb 


1 








1 


mo lo 










0-9 




1 





1 





mo hi 




• 


* 




0-1 




1 





1 


1 


yr lo 










0-9 




1 


1 








yr hi 










0-9 





* Unused bits 

A Bits used for AM/PM, 12/24 hr, and leap year 

Table 1. Clock address codes. (From the March 1980 MSM5832 data sheets supplied by OKI 
Semiconductor, 1333 Lawrence Expressway, Santa Clara, CA.J 



line, signalling the processor that the 
interrupt has occurred. Once set, the 
interrupt flags can be cleared directly 
by writing a 1 to that bit of the IFR, or 
indirectly as defined in Table 3. 

Table 4 shows the address codes 
and functions of all 16 registers of the 
6522. 

Putting It All Together 

The circuit schematic (Fig. 2) shows 
the interconnection of the MSM5832, 
6522 and supporting circuitry, and 
the required connections to the Apple 
bus. 

The lower four lines of port B and 
the upper four lines of port A on the 
6522 are used as control outputs to 
the clock chip, while the lower four 
lines of port A are connected to the 
clock data lines. These lines are used 
as outputs when writing to the clock 



Conditions 

hold = low 
read = high 
c.s. = high 
A -A 3 = high 



Output Frequency Pulse Width 



Doll) 
D, 
D 2 
D. 



1024 Hz 

1 Hz 

1/60 Hz 

1/3600 Hz 



50% duty 
122.1 us 
122.1 us 
122.1 us 



(1) 1024 Hz output is independent of hold input. 
Table 2. Pulse outputs. (From the MSM5832 data sheets.) 



and as inputs when reading the clock. 
The CA2, CB1 and CB2 lines are also 
connected to the data lines so that the 
timing pulses on these lines (once/ 
second, once/minute, and once/hour) 
can be used as programmable inter- 
rupts. The 1024 Hz signal from DO of 
the 5832 is connected to the 6522's 
PB6 input for use in conjunction with 
timer T2, as described earlier. 

In addition to the two main ICs, it is 
necessary in this circuit to provide 
the address decode for the 6522 chip 
select. The objective here is to use the 
16 peripheral I/O addresses, which 
Apple has reserved for each card slot, 
to address the 16 6522 registers. 
These addresses are between $C0n0 
and $C0nF, where n is the slot num- 
ber plus $8 ($ indicates a hexadeci- 
mal number). 

The Apple peripheral bus provides 
a decoded access signal (device se- 
lect) for this purpose, but unfortu- 
nately, it becomes active coincident 
with the rising edge of the phase 
clock. That is too late for the 6522, 
which requires that the register select 
and chip select lines be stable 180 ns 
prior to the clock. We can meet that 
requirement if we decode the chip se- 
lect directly from the address bus as 
shown, using 74LS127 and 74LS130 
gates. The gate connections shown in 



Microcomputing, August 1981 117 



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Bit # Set by 

Active transition of the signal on the 
CA2 pin. 

1 Active transition of the signal on the 
CA1 pin. 

2 Completion of eight shifts. 

3 Active transition of the signal on the 
CB2 pin. 

4 Active transition of the signal on the 
CB1 pin. 

5 Time-out of Timer 2. 

6 Time-out of Timer 1. 



Reading 
Register 
Reading 
Register 
Reading 
Reading 
Register 
Reading 
Register 
Reading 
T2 high 
Reading 
Tl high 



Cleared By 

or writing the A port Output 
(ORA) using address 0001. 
or writing the A Port Output 
(ORA) using address 0001. 
or writing the Shift Register, 
or writing the B Port Output 

or writing the B Port Output 

T2 low order counter. Writing 
order counter. 

Tl low order counter. Writing 
order counter. 



Table 3. Interrupt flag register. (From the Jan. 1 978 SY6522 data sheets supplied by Synertex, PO 
Box 552, Santa Clara, CA.) 



the schematic assume that you are in- 
stalling the clock card in slot 4. Table 
5 gives alternate connections for 
other slots. 

The only other active circuit ele- 
ment required is the inverting circuit 
that drives the 5832 chip select line. 
This is necessary because a reset, 
which occurs when you turn the Ap- 
ple on or press reset, causes the 6522 
to go into a state in which all of the 
I/O lines are in the high-impedance 
input mode. Since these lines have in- 
ternal pull-up resistors, they look at 
that point like logic 1 signals to the 
5832 inputs, one of which is the hold 
line. A reset would therefore stop the 
clock. 

By connecting the chip select as 
shown, you can deselect the 5832 
when the reset occurs. In this condi- 
tion the clock continues to count, 
since the hold and all other inputs are 
disabled. The next write or read to 
the clock card can then set the control 



inputs back to the proper states. 

The battery provides power to 
keep the clock running when the 
computer is off. The specifications 
say that a minimum of 2.2 V are re- 
quired in the standby mode, so a bat- 
tery supply of about 3 V is adequate. 
The specified battery current is 30 
microamps (maximum) at 3 V, but 
measurements on a couple of sam- 
ples showed only 5 to 7 microamps. 
At that rate a wide range of batteries 
would be suitable, including some of 
the button cells used in watches and 
calculators. Rechargeable cells could 
be used of course, but, considering 
the low current drain and consequent 
long life available from nonrecharge- 
able cells, I did not feel that recharg- 
ing was worth the extra circuitry re- 
quired. 

The final choice of battery in my 
case boiled down to one which was 
readily available and easy to connect. 
Ease of connection was important 



Register 
Number 


1 

2 
3 

4 
5 

6 

7 

8 

9 
10 
11 
12 
13 
14 
15 



RS3 










1 
1 
1 
1 
1 
1 
1 
1 



RS Coding 
RS2 RSI 








1 
1 
1 
1 






1 
1 
1 
1 






1 
1 




1 
1 




1 
1 




1 
1 



Register 
RSO Desig. 

ORB/IRB 

1 ORA/IRA 

DDRB 

1 DDRA 

T1C-L 

1 T1C-H 

TILL 

1 T1L-H 

T2C-L 

1 T2C-H 

SR 

1 ACR 

PCR 

1 IFR 

IER 

1 ORA/IRA 



Description 



Write 



Read 



Output Register "B" Input Register "B" 

Output Register "A" Input Register "A" 

Data Direction Register "B" 

Data Direction Register "A" 

Tl Low-Order Latches Tl Low-Order Counter 

Tl High-Order Counter 

Tl Low-Order Latches 

Tl High-Order Latches 

T2 Low-Order Latches 

T2 High-Order Counter 

Shift Register 

Auxiliary Control Register 

Peripheral Control Register 

Interrupt Flag Register 

Interrupt Enable Register 

Same as Reg 1 Except No "Handshake" 



T2 Low-Order Counter 



Table 4. 6522 address codes. (From the SY6522 data sheets.) 



118 Microcomputing, August 1981 



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Microcomputing, August 1981 119 



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Prices do not include shipping VISA and Master Charge add 3% 
COO orders require 25% deposit Prices subject to change without 
notice 



Slot 


Address 


9 


1 


C09x 


GND 


2 


COAx 


GND 


3 


COBx 


GND 


4 


COCx 


GND 


5 


CODx 


GND 


6 


COEx 


GND 


7 


COFx 


GND 


* requires inverting 


A4 



74LS27 






74LS30 




10 


11 


4 


5 


12 


A5 


A6 


A4 


A7 


PUB 


A4 


A6 


A5 


A7 


PUB 


GND 


A6 


A4 


A5 


A7 


A4 


A5 


A6 


A7 


PUB 


GND 


A5 


A4 


A6 


A7 


GND 


A4 


A5 


A6 


A7 


GND 


A4* 


A5 


A6 


A7 



Table 5. Chip select address decode. 



because many candidate cells, such 
as the button types, require special 
clips or holders that are not generally 
available. My choice was a single 3 V 
alkaline cell (#532), which is avail- 
able in camera shops. It features snap 
contacts, like those on 9 V transistor 
batteries, which provide a quick and 
positive connection. This battery 
should provide several years of ser- 
vice. 

The diodes provide the required 
isolation between the battery and the 
computer's 5 V bus. Germanium di- 
odes (1N270) were used because of 
their low (0.2 V) forward voltage 
drop. The series resistor is optional. I 
put it in just to provide some isolation 
to the battery in the event of a diode 
short. 

Construction 

The circuit was constructed on an 
Apple prototype card, using sockets 
for the ICs. You can take your choice 
of wiring method. I used solder con- 
nections with #30 solid conductor in- 
sulated wire-wrap wire. That type of 



wire is easily formed around the 
socket pins, solders easily, and will 
lie flat against the card even when 
there is excess length. 

The only awkward part of building 
up the card is the battery mounting. 
If you use the suggested battery you 
will find that it can be mounted di- 
rectly on the card, but will cause a 
tight fit with respect to the next high- 
er card. You could eliminate that 
problem by using slot 7. Otherwise, if 
you put the battery on the card, be 
sure to insulate the case so that it 
won't short anything. My solution 
was to mount the battery on the in- 
side of the computer case using a 
stick-on wire tie pad. A pair of wires 
then connect the battery to the card. 
Not elegant, but practical. One ad- 
vantage is that a battery leak won't be 
likely to seriously damage anything. 

There is one option not shown in 
the schematic that you may be inter- 
ested in. The 5832 has an ADJ input 
(pin 15), which is shown connected to 
ground. If you wish, you can connect 
that pin through a momentary con- 



INTERRUPT 
CONTROL 



DATA 
BUS 



c=> 



DATA 

BUS 

BUFFERS 



FLAGS 
(IFR) 



rV ENABLE 



ENABLE 
(IER) 



3 



RES 
R/W 

CSI 

CS2 

RSO 

RSI 

RS2 

RS3 



CHIP 

ACCESS 

CONTROL 



PERIPHERAL 
(PCR) 



r—S AUXILIARY 



AUXILIARY 
(ACR) 



FUNCTION 
CONTROL 



LATCH 
(TIL-H) 



LATCH 
(TIL-L) 



r-V COUNTER ! COUNTER 



COUNTER I COUNTER 
(TIC-H) (TIC-L) 



INPUT LATCH 
(IRA) 

OUTPUT 
(ORA) 

DATA DIR 
(DDRA) 



BUFFERS 
(PA) 



O» 0RT 



PORT A 
REGISTERS 



Z> 



TIMER I 
TIMER 2 



o 



COUNTER 
(T2C-H) 



LATCH 
(T2L-L) 

COUNTER 
(T2C-L) 



PORT A 
PORT B 


























HANDSHAKE 
CONTROL 






SHIFT REG 
(SR) 

















CAI 
CA2 



CBI 
CB2 



PORT B REGISTERS 



3 



INPUT LATCH 
(IRB) 

OUTPUT 
(ORB) 

DATA DIR 
(DDRB) 



o 



BUFFERS 
(PB) 



O 



PORT 
B 



Fig. 1. SY6522 block diagram. (From the SY6522 data sheets.) 



120 Microcomputing, August 1981 



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YOU NEED MORE ROOM... 




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host of new features. Like the availability of a 
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cursor, monitor band width and display of 
control characters. 

Moreover, DoubleVision is compatible with 
CCA Data Management (and full screen map- 



DOUBLEVISION™ 

80 x 24 Video Display 
from Computer Stop 



ping), Easywriter Professional System, Apple 
Pie 2.0, PASCAL, Z-80 Softcard, MAGIC- 
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It's the only 80-column card that has software 
on disk making it easy to provide updates. In 
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If 



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ur 010081 
















I6K RAM t 

by computer stop , n 

' imiiiiiiiiimiiiir 



When you add the CS16K RAM Card to 
your Apple II with 48K bytes of RAM 
already in place, you immediately increase 
your capacity to 64K. 

The CS16K RAM Card is compatible with 
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CP/M is a trademark of Digital Research 



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Torrance, CA 90505 
(213) 539-7670 

Dealers: Ask about 
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*sSee List of Advertisers on page 194 



Microcomputing, August 1981 121 



Now with added words/ * 

ELECTRIC MOUTH 




%S?lZ':;*~ "-$99,951* 

Now — teach your computer to talk, 
increasing interaction between you 
and your machine. 

That s right the ELECTRIC MOUTH actually lets your computer talk' Installed 
and on-line in just minutes, it's ready for spoken -language use m office, busi- 
ness industrial and commercial applications and in games, special projects. 
RAD. eduction security devices — there s no end to the ELECTRIC MOUTH's 
usefulness I>x>k al these features 

• Supplied with 143 letters/words/phonemes/numhers capable of producing 
hundreds of words and phrases 

• Expandable on Ixiard up to thousands of words and phrases with additional 
■OMCfc ROMs (see new spe«-<;h ROM desc:ribed below) 

• Four rmidels that plug directly into S100. Apple. Elf II and TRS-80 Level II 
computers 

• ( iet KI.EC : IRK : MOt FT1 1 to talk with either Basic or machine language (very 
easy to use complete instructions with examples included) 

• s National Semiconductor s "Oigitalker 

• Includes onboard audio amplifier and speaker, with provisions for external 
speakers 

• Installs in just minutes 

Principle of Operation: The ELECTRJC MOUTH stores the digital equivalents 
of words in ROMs When words, phrases and phonemes are desired, they 
simply are called for by your program and then synthesized into speech. The 
ELECTRIC MOI ri'M system requires none of your valuable memory space ex 
<;ept for a few addresses if used in memory mapped mode In most cases output 
ports (user selectable) are used 



one 

two 

three 

four 

five 

six 

seven 

eight 

nine 

ten 

eleven 

twelve 

thirteen 

fourteen 

fifteen 

sixteen 

seventeen 



SPOKEN MATERIAL INCLUDED (Vox I) 
eighteen at dollar inches number 
nineteen cancel down is of 
twenty case equal it otf 
thirty cent error kilo on 
forty 400hertz tone feet left out 
fifty aohertz tone flow less over 
sixty 20ms silence fuel lesser 
seventy 40ms silence gallon limit percent 
eighty 80ms silence go low please 
ninety 180ms silence gram lower plus 
hundred 320ms silence great mark point 
then i shim I cent i greater meter pound 
million check have mile pulse- 
zero comma high milli rate 
again control higher minus re 
ampere danger hour minute ready 
and degree in near right 



ss 

second 

set 

space 

S(»'fll 

star 



parenthesis start i 



u 
v 
w 

X 

y 

z 



stop 

than 

the 

time 

try 

up 

volt 

weight 

a 

b 



1 

m 

n 

o 

P 

q 

r 

s 



ADDITIONAL VOCABULARY NOW AVAILABLE (VOX II) 



abort 

add 

adjust 

alarm 

alert 

all 

ask 

assistance 

attention 

blue 

brake 

button 

buy 

call 

called 

caution 

celsius 

centigrade 

change 

circuit 

cigar 

close 

mid 



complete 
continue 

c<>py 

uirrect 
GMM 

<ie 
deposit 
dial 
door 
east 
"ed" 

emergency 
enter 
entry 
"er" 

eth 
evacuate 
exit 
fail 

failure 
fahrenheit 
fast 
faster 



fifth 

fire 

first 

floor 

fourth 

forward 

from 

gas 

get 

gomg 



an* 

hale 

heat 

hello 

help 

hurts 

hold 

hot 

in 

i nt airrect 

intruder 

key 

level 



light 

load 

lock 

longer 

more 

move 

next 

no 

normal 

north 

not 

notice 

open 

operator 

or 



per 

power 

press 

pressure 

process 

pull 

push 



put 

quarter 

range 

reached 

receive 

record 

reverse 

red 

repair 

repeat 

replace 

room 

safe 

second 

secure 

select 

send 

service 

side 

slow 

slower 

smoke 

south 



station 

switch 

system 

.emperature 

test 

•th 

thank 

third 

this 

turn 

under 

use 

waiting 

warning 

was 

water 

west 

wind 

window 

yellow 

yes 

zone 



L 



*Rqgisterad Dtademarifs 



■ Continental U.S.A. Credit Card Buyers Outside Connecticut ■ 

■ — 

p 



TO ORDER 
I Call Toll Free: 800-243-7428 

t To Order From Connecticut, or For Technical 
Assistance, call (203) 354-9375 

NETRONICS R&D LTD. 

333 Litchfield Road, New Milford, CT 06776 

DeptK8 



ISN 



I Please send the items checked below: 

• 

■ D SlOO "Electric Mouth" kit w Vox I $ 99.95 

! □ Elf II "Electric Mouth" kit w/Vox I $ 99.95 

■ D Apple "Electric Mouth" kit w/Vox I $119.95 

■ □ TRS-80 Level II "Electric Mouth" kit w/Vox I $119.95 

J D VOX II (Second Word Set) $ 39.95 

J Add $20 (M) for wired trsle<l units instead of kits VOX II postage * insurance 
I $1 00 .ill others $3.00 postage and insurance CoM res add sales I. ix 

5 Total Enclosed $ 

■ 

JD Personal Check D Cashier's Check/ Money Order 

' □ Visa D Master Charge (Bank No. ) 

■ 

5Acct.No. Exp. Date 



■ Signature 
I Print 
; Name 



■ Address 

■ City 



State 



Zip. 



♦ 5V 

o 

GND 

o- 

D0 

o 

Dl 

o 

D2 

O 

03 

O 

D4 



25 



26 



49 



48 



47 



46 



05 

O 
06 
O 



45 



44 



43 



R/W 



o 

$0 

g> 

IRQ 

o- 

A0 

o 

At 



18 



40 



30 



L3^- 

A2 
A3 
RES 



O 



1 



0\fiF 



i 



0.1-F 



33 



32 



31 



30 



29 



28 



27 



26 



22 



IN270 



IN270 



20 



25 



21 



38 



37 



36 



35 



34 



vss 

DO 

01 

02 

D3 

D4 

05 

06 

D7 

R/W 

CLK 

Fro 
rso 

RSI 
RS2 
RS3 
RES 

est 



vec 

6522 



CAI 
PA0 
CA2 
PA I 
CBI 
PA2 
CB2 
PA 3 
PA 4 
PA5 
PA6 
PA 7 
PB0 
PBI 
PB2 
PB3 
PB6 



40 



^ 



39 



18 



19 



10 



12 



vec 

MSM5832 
00(I024Hj) 



f — w — i — wv — 



to 



1 1 



12 



13 



16 




18 



OKI/SEC) 

D2( l/MINI 

03II/HR) 

A0 

At 

A2 

A3 

HOLD 

READ 

WRITE 



XT 



XT 



ADJ 
TEST 

GND 



CS 



3V BATTERY ^ 
TYPE 532 



i 



16 



3-l8pF 

-JF- 



- CRYSTAL 
^ 32 768KH2 



17 



20pF 

-ir- 



15 



14 



13 



74LS00 



o- 



I ON I/O CONNECTOR JUMPER 24-27(DMA) 
AND 23-28 (INT) 

2. V cc 8 GND FOR LSXX CHIPS NOT SHOWN 
PIN 7» GND. PIN 14* Vcc 

ADDRESS DECODE FOR SLOT 4 SHOWN 



Fig. 2. Apple clock I calendar. 



Listing 1. Set Clock routine. 



10 

12 

14 

16 

18 

20 

30 

40 

50 

60 

70 

80 

90 

92 

94 

99 

100 

110 

120 

130 

140 

150 

160 

180 

200 

210 

220 

240 

260 

350 

360 

370 

400 

410 

420 

430 

440 

460 

430 

490 

500 

520 

540 

550 

560 

580 

600 

610 

620 

650 

660 

670 

680 

690 

700 

710 



REM 
REM 
REM 
REM 
REM 
REM 



*********************** 

* > 

* SET CLOCK ROUTINE * 
« D.G0SS 22 AUG 80 $ 

* * 

*********************** 



REM * SET LY=1 TO ENAB LEAP YEAR OPTION 




= 4 

49280 
39000 



4 SLOT * 16t 
REM ADDR OF 



* ROUTINE EXITS WITH CLK/TIMER INTERRUPTS DISABLED 



LY = 

SLOT 

BA - 

RC = 

• 

'rem 

» 

*B* = CHR* <7>:D$ = CHR$ (4) 

PRINT D*»"BL0AD READ CLOCK" 

HOME J VTAB 3 

PRINT "ENTER TIME: HH MM" 

VTAB 31 HTAB 13 

INPUT "" JT* 
HI = VAL ( LEFT$ < T*»l >) 

IF HI > 1 THEN 800 
H2 ■ VAL ( MID* ( T*»2»l )) 

IF HI = 1 AND H2 > 2 THEN 800 
Nl = VAL ( MID* (T*f4»l )) 

IF Nl > 5 THEN 800 
N2 = VAL ( MID* ( T*f5»1 )) 

VTAB 5 

INPUT "AM OR PM? "JM* 

IF M* "AM" AND M0 < > 

VTAB 7 

PRINT "ENTER DATE: MM DD YY' 

VTAB 71 HTAB 13 

INPUT "";D* 
Ml = VAL ( LEFT* ( D*f 1 )) 

IF Ml 1 THEN 850 
M2 = VAL ( MID* (D*»2f 1 )) 

IF Ml = 1 AND M2 > 2 THEN 
Dl = VAL ( MID* ( D*f4»l )) 

IF Dl 3 THEN 850 
D2 ■ VAL ( MID* (D*»5t 1 )) 

IF Dl = 3 AND D2 1 THEN 
Yl = VAL ( MID* ( D*»7t 1 ) ) 
Y2 = VAL ( MID* ( D*r8rl )) 

PRINT 

IF NOT LY THEN 650 

INPUT "LEAP YEAR? ( Y/N ) 

PRINT : PRINT 

INPUT " PRESS RETURN 

PRINT : PRINT 

G0SUB 1000 

PRINT "CLOCK NOW READS 



REM BASE 1/0 ADDR 
RD CLK PROG 



PM" THEN PRINT B0 t GOTO 350 



850 



850 



-JL* 
TO SET 



CLOCK " f A* 



i : 



CALL RC: PRINT 



PUKE BA»0: REM RELEASE HOLD 




122 Microcomputing, August 1981 



Listing 


1 continued. 










720 


PRINT 


: PRINT 






730 


END 










79? 


* 
• 










800 


REM * 


TIME 


INPUT 


ERROR 




810 


PRINT 


B$ 








820 


GOTO . 


120 








849 


• 
• 










850 


REM * 


DATE 


INPUT 


ERROR 



860 

870 

999 

1000 

1010 

1020 

1030 

1040 

1050 

1060 

1070 

1080 

1090 

1100 

1110 

1120 

1130 

1140 

1150 

1160 

1170 

1180 

1200 

1210 

1220 

1230 

1240 

1250 

1260 

1270 

1280 

1290 

1300 

1310 

1320 

1330 

1999 

2uu«j 

2010 

2030 

2040 



PRINT B$ 
GOTO 400 

REM * SET T 

RA = BA + i: 
POKE BA 4 1 
POKE BA 4 3 
POKE BA 4 
POKE BAfll 
IF M$ = "AM 



I ME 

REM ORA ADDR 
4,127 1 REM DISAB INTERRUPTS 



IF M$ = "PM 
GOSUB 2000 
POKE RA,64 
GGSUB 2000 
POKE RA.48 
GOSUB 2000 
POKE RAf32 
GOSUB 2000 
POKE RAtl6: 
GOSUB 2000 

POKE ra»o: : 

GOSUB 2000 
POKE RA-160 
GOSUB 2000 
POKE RA»144 
GOSUB 2000 
IF L$ < > 
IF L$ = M Y" 
GOSUB 2000 
POKE RA»112 
GOSUB 2000 
POKE RArl92 
GOSUB 2000 
POKE RA,176 
GOSUB 2000 
RETURN 



HR HI, AM 
HR HI-PM 



,255: REM DDR A 

,15: REM DDRB 

REM SET HOLD 

" THEN POKE RA»80 4 Hi: REM 

" THEN POKE RA,84 4 HI! REM 

4 H2: REM HR LO 

4 Ni: REM MI LO 

4 N2: REM MI HI 

REM SEC HI = 

REM SEC LO = 

4 Mi: REM MO HI 

4 M2: REM MO LO 

"iT„-J HEN o.£ £§ S3* 1 ? 8 + D1: REM DAY HI, NORM 
THEN POKE RA,132 4 Dl : REM DAY HI* LEAP YR 

4 D2 

4 Ylt REM YR HI 

4 Y2t REM YR LO 



REM * WRITE DATA 

POKE BA,5: REM WRITE ON 

POKE BA,i: REM WRITE OFF 

RETURN 



Listing 2. Read Clock routine. 



0800 


1 








0800 


2 


,READ 


CLOCK 


0800 
0800 


3 


»REAL 


TIME 


CLOCK 


4 


5SL0T 


4 




0800 


5 








0800 


6 


i VERS 10 


.6 


0800 


7 


,07 SEP 


0800 


8 








0800 


9 


PRBL2 


EQU 


tF94A 


0800 


10 


IOSAOE 


EQU 


♦FF4A 


0800 


11 


IOREST 


EQU 


♦FF3F 


12 


WAIT 


EQU 


♦FCA8 


0800 


13 


COUT 


EQU 


fFDED 


0800 


14 


IORB 


EQU 


♦COCO 


0800 


15 


IORA 


EQU 


9C0C1 


0800 


16 


DDRB 


EQU 


♦C0C2 


0800 


17 


DDRA 


EQU 


9COC3 


0800 


18 


H10SA0 


EQU 


♦04 7C 


0800 


19 


TDFLAG 


EQU 


♦05 7 C 


0800 


20 


ORBSAO 


EQU 


♦067C 


0800 


21 


* 

t 






9858 


22 




ORG 


♦9858 


9858 


23 




OBJ 


♦0800 


9858 


24 


• 






9858 204AFF 


25 


ENTRY 


JSR 


IOSAVE 


985B A900 


26 




LDA 





985D 8D7C05 


27 




STA 


TDFLAG 


9860 F012 


28 




BEQ 


SETUP 


9862 204AFF 


29 


TONLY 


JSR 


IOSAVE 


9865 A901 


30 




LDA 


1 


9867 8D7C05 


31 




STA 


TDFLAG 


986A D008 


32 




BNE 


SETUP 


986C 204AFF 


33 


PONLY 


JSR 


IOSAOE 


986F A902 


34 




LDA 


•t 


9871 8D7C05 


35 




STA 


TDFLAG 


9874 78 


36 


SETUP 


SEI 




9875 ADCOCO 


37 




LDA 


IORB 


9878 8D7C06 


38 




STA 


ORBSAV 


987B A9F0 
987D 8DC3C0 


39 




LDA 


OFO 


40 




STA 


DDRA 


9880 A90F 


41 




LDA 


OF 


9882 8DC2C0 


42 




STA 


DDRB 


9887 8DCOC0 


43 
44 




LDA 
STA 


1 
IORB 


988A A906 


45 




LDA 


6 


988C 20A8FC 


46 




JSR 


WAIT 


988F A903 


47 




LDA 


3 


9891 8DCOC0 


48 




STA 


IORB 


9894 


49 


J 






9894 AD7C05 


50 




LDA 


TDFLAG 


9897 C902 


51 




CMP 


2 


9899 F05B 


52 




BEQ 


DATE 


989B A950 


53 




LDA 


50 


989D 203999 


54 




JSR 


READ 


98A0 8D7C04 


55 




STA 


H10SA0 


98A3 2903 


56 




AND 


3 


98A5 204 C 99 


57 




JSR 


PRINT 


98A8 A940 


58 




LDA 


40 


98AA 204 399 


59 




JSR 


RD.PT 


98AD A9BA 


60 




LDA 


OBA 


98AF 20EDFD 


61 




JSR 


COUT 


98B2 A930 


62 




LDA 


30 


98B4 204 399 


63 




JSR 


RD.PT 


98B7 A920 


64 




LDA 


20 


98B9 204399 


65 




JSR 


RD.PT 


98BC A9BA 


66 




LDA 


OBA 


98BE 20EDFD 


67 




JSR 


COUT 


98C1 A910 


68 




LDA 


10 


98C3 204399 


69 




JSR 


RD.PT 


98C6 A900 


70 




LDA 





98C8 204 399 


71 




JSR 


RD.PT 


98CB A9A0 


72 




LDA 


OAO 


98CD 20EDFD 


73 




JSR 


COUT 



fTIME/DATE ENTRY 
JTIME ONLY ENTRY 

JDATE ONLY ENTRY 

fDISAB 6502 IRQ 

fSAVE ORB CONTENTS 

JPA0-PA3 IN,PA4-PA7 OUT 

JPB0-PB3 0UT,PB4-PB7 IN 

J SET CLK HOLD 

JDELAY 150 USEC 

J SET CLK HOLD & READ 



fREAD DATE ONLY? 
J IF YES GO DATE 

,READ HR HI 

rSAUE BYTE 

JMASK INVALID BITS OFF 

JPRINT HR HI 



{OUTPUT HR LO 
rPRINT COLON 
fOUTPUT MIN HI 
fOUTPUT MIN LO 
rPRINT COLON 
fOUTPUT SEC HI 
fOUTPUT SEC LO 
f SPACE 




MMSFORTH VERSION 2.0: 

MORE FOR YOUR RADIO SHACK 
TRS-80 MODEL I OR MODEL III ! 



• MORE SPEED 

10-20 times faster than Level 



BASIC. 



• MORE ROOM 

Very compact compiled code plus VIRTUAL 
MEMORY makes your RAM act larger. Variable 
number of block buffers. 31-char. -unique word- 
names use only 4 bytes in header! 

• MORE INSTRUCTIONS 

Add YOUR commands to its 79-STANDARD-plus 

instruction set! 

Far more complete than most Forths: single & 

double precision, arrays, string-handling, clock, 

more. 

• MORE EASE 

Excellent full-screen Editor, structured & 

modular programming 

Word search utility 

NOTEPADS Letter writer 

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Microcomputing, August 1981 123 





















Listing 2 continued 
















98D0 


AD7C04 


74 




LDA 


H10SAV 








mi 


6A 
6A 


Vi 




ROR 
ROR 










98D5 


6A 


77 




ROR 










98D6 


B008 


78 




BCS 


PRINTP 




{IF AM/PM IS PM PRINT "P" 




98D8 


A9C1 


79 




LDA 


0C1 








98DA 


20EDFD 


80 




JSR 


COUT 




{ELSE PRINT "A" 




98DD 


4CE598 


81 




JMP 


PRINTM 








98E0 


A9D0 


82 


PR1NTP 


ODO 








98E2 


20EDFD 


83 




JSR 


COUT 




{PRINT "P" 




98E5 


A9CD 


84 


PRINTM 


OCD 








98E7 


20EDFD 


85 




JSR 


COUT 




{PRINT H M H 




98EA 




86 


■ 












98EA 
98ED 


AD7C05 


87 




LDA 
CMP 


TDFLAG 








C901 


88 




1 




{TIME ONLY? 




98EF 


F032 


89 




BEQ 


EXIT 




{IF SO EXIT 




98F1 




90 


• 

t 












m 


A202 


91 




LDX 
JSR 


2 








204AF9 


92 




PRBL2 




12 SPACES 




98F6 


A9A0 


93 


DATE 


LDA 


OAO 








98F8 


204399 


94 




JSR 


RD.PT 




{OUTPUT MO HI 




98FB 


A990 


95 




LDA 


90 








98FD 


204399 


96 




JSR 


RD.PT 




{OUTPUT MO LO 




9900 


A9AF 


97 




LDA 


OAF 








9902 


20EDFD 


98 




JSR 


COUT 




JPRINT SLASH 




9907 203999 


99 
100 




b^ 


READ 




{READ DAY HI 




990A 


2903 


101 




AND 


03 




{MASK LEAP YR BITS OFF 




990C 


204C99 


102 




JSR 


PRINT 








990F 


A970 


103 




LDA 


70 








9911 


204399 


104 




JSR 


RD.PT 




{OUTPUT DAY LO 




9914 


A9AF 


105 




LDA 


OAF 








9916 


20EDFD 


106 




JSR 


COUT 




JPRINT SLASH 




lllg 


A9C0 


107 




LDA 


OCO 








204399 


108 




JSR 


RD.PT 




fOUPUT YR HI 




991E 


A9B0 


109 




LDA 


OBO 








9920 


204399 


no 




JSR 


RD.PT 




{OUTPUT YR LO 




9923 




111 


• 

r 












9923 


A9A0 


112 


EXIT 


LDA 


OAO 








9925 


20EDFD 


113 




JSR 


COUT 




{SPACE 




9928 


A9F0 


114 




LDA 


OFO 








992A 


8DC1C0 


115 




STA 


IORA 




{CLK ADDR = ♦F 




992D 


AD7C06 


116 




LDA 


ORftSAV 








9930 


290F 


117 




AND 


OF 




{SET UNUSED BITS TO ZERO 




9932 


8DCOC0 


118 




STA 


IORB 




{RESTORE ORB 




9935 


203FFF 


119 




JSR 


IOREST 




{RESTORE 6502 REGISTERS 




9938 


60 


120 




RTS 










9939 




121 














9939 




122 


{SUBRO 








9939 




123 














9939 


8DC1C0 


124 


READ 


STA 


IORA 




JSET READ ADDR 




993C 


EA 


125 




NOP 










993D 


EA 


126 




NOP 










993E 


EA 


127 




NOP 






J DELAY 6 USEC 




993F 


ADC ICO 


128 




LDA 


IORA 




{READ DATA 




9942 


60 


129 




RTS 










9943 




130 


• 

t 












9943 


8DC1C0 


131 


RD.PT 


STA 


IORA 




JSET READ ADDR 




9946 


EA 


132 




NOP 










9947 


EA 


133 




NOP 










9948 


EA 


134 




NOP 






{DELAY 6 USEC 




9949 


ADC ICO 


135 




LDA 


IORA 




{READ DATA 




994C 




136 


• 

r 












994 C 


290F 


137 


PRINT 


AND 


OF 




{CLEAR BITS 4-7 




994E 


09B0 


138 




ORA 


OBO 




{CONV TO ASCII 




9950 


20EDFD 


139 




JSR 
RTS 


COUT 




{PRINT CHAR 




9953 


60 


140 












9954 




141 
142 


• 

f 


END 








0800 




1 


• 

1 












0800 




*> 

4. 


iCLOCh 


; DEMO 










0800 




3 


{VERSION 1. 


1 








0800 




4 


{07 SEFT 80 










0800 




5 














0800 




6 


HOME 


EQU 


♦FC58 








0800 




7 


IOSAVE EQU 


SFF4A 






. 


0800 




8 


IOREST EQU 


♦FF3F 








0800 




9 


IORft 


EQU 


♦ COCO 








0800 




10 


IORA 


EQU 


♦ C0C1 








0800 




11 


DDR F< 


EQU 


♦ C0C2 








0800 




12 


DDRA 


EQU 


♦C0C3 








0800 




13 


PCR 


EQU 


♦ COCC 








0800 




14 


IFR 


EQU 


$COCD 








0800 
0800 




15 


IER 


EQU 


♦ COCE 










16 


RDCLK 


EQU 


♦9858 








0800 




17 


• 

t 












9960 




18 




ORG 


♦9960 








9960 




19 




OBJ 


♦0800 








9960 
9960 


78 


20 
21 


* 

ENTRY 


SEI 






{DISABLE 6502 INTERRUPTS 


9961 


2058FC 22 




JSR 


HOME 








9964 
9966 


A900 23 
8DCCC0 24 




LDA 
STA 


♦♦00 
PCR 




{PROG 


CA2 FOR INPUTf NEG ACTIVE EDGE 


9969 
996ft 


A9F0 25 
8DC3C0 26 




LDA 
STA 


♦ ♦FO 
DDRA 




{ENABLE CLK ADDR OUTPUTS 


996E 


8HC1C0 27 




STA 


IORA 




{SET 


CLK ADDR IU %*■ 


9971 
9973 


A90F 28 
8DC2C0 29 




LDA 
STA 


♦ ♦OF 
DDRB 




JENABLE CLK CONTROL OUTPUTS 


9976 
9978 


A902 30 
8DC0C0 




LDA 
STA 


#♦02 
IORB 




{TURN 


READ CMD ON 


997P 


A981 


32 




LDA 


•♦81 








997 D 


8DCEC0 33 




STA 


IER 




fENABL 


9980 
9982 


A9A1 34 
8DFE03 35 




LDA 
STA 


♦INTRPT 
♦ 3FE 


{SET 


INTERRUPT VECTOR LO 


9985 


A999 


36 




LDA 


/INTRPT 






9987 


8DFF0* 




STA 


♦ 3FF 




{SET 


INTERRUPT VECTOR HI 


998A 


58 


3R 




CLI 






JENABLE 6502 INTERRUPTS 


998ft 


2C00C0 


KEY IN 


BIT 


♦COOO 




J CHECK FOR ANY KEY 


998E 


lOFft 


40 




BPL 


KEYIN 




{IF NOTf CHECK AGAIN 


9990 


2C1OC0 41 




BIT 


♦CO10 




{ELSE 


CLEAR KEY STROBt 


999 3 
9995 


A97F 42 
8DCEC0 43 




LDA 
STA 


♦ *7F 
IER 




{DISABLE 6522 INTERRUPTS 


9998 


A900 


44 




LDA 


•♦0 








999A 
999 D 


BUCOCO 45 
78 46 




STA 
SEI 


IORB 




{TURN 

fDISABLE 6502 INTERRUPTS 


999E 


4C69FF 




JMP 


♦ FF69 




{RETURN TO MONITOR 


99A1 




48 


• 












99A3 
99A3 


A909 
8524 


49 

50 
»8 51 


INTRPT LDA 
STA 


♦ ♦09 

♦ 24 




{CENTER PRINTOUT ON CRT 


99A5 


2058S 




JSR 


RDCLK 




{OUTPUT TIME/DATE 


99 A 8 
99AA 


A901 52 
8DCDC0 




LDA 
STA 


♦♦01 
IFR 




{CLEAR CA2 INTERRUPT FLAG 


99AIi 


40 


5* 




RTI 






{RETURN 


99AE 




55 
56 


• 


END 




















Listing 3. Clock Demo 


. 



tact switch to Vcc or to the pull-up re- 
sistor. Depressing the switch will 
then cause the clock's second-count- 
er to reset to 0. The minute-counter 
will remain unchanged if the seconds 
count was less than 30, but will ad- 
vance one minute if the seconds 
count was 30 or more. 

I had some trouble locating all of 
the parts for the circuit, particularly 
the clock chip and crystal. I finally 
found that Advanced Computer Prod- 
ucts (PO Box 17329, Irvine, CA 
92713) had everything I needed. 

Making It Play 

The trimmer capacitor in the cir- 
cuit provides a method of fine-tuning 
the oscillator for accuracy. Getting it 
set correctly will probably require 
some trial-and-error attempts over an 
extended period of time, but to start 
with, just set it at the midpoint and 
you should be close. When adjusting, 
you add capacitance to slow the clock 
down, and subtract to speed it up. 
The adjustment is sensitive, so use 
small increments. With a little pa- 
tience you should be able to get it ac- 
curate to within one second/week or 
better. 

To use the clock/calendar your pro- 
grams must first set up the 6522 regis- 
ters, and then write to or read from 
the 5832, one BCD digit at a time. 
Sample program listings are included 
to get you started. To understand 
how things work, it might be helpful 
to go through an explanation using 
the Set Clock program (Listing 1) as 
an example. This Applesoft program 
allows the clock and calendar to be 
set from the keyboard. It programs 
the clock in the 12-hour mode and in- 
cludes a leap year option, but does 
not set day of week. 

The actual clock setting routine be- 
gins at line 1000, using time and date 
variables input in lines 100 through 
670. Line 1020 makes sure that all 
6522 interrupts are disabled by writ- 
ing a $7F to the IER. (Interrupts are 
selectively enabled/disabled by writ- 
ing to the IER with a 1 or 0, respec- 
tively, in bit 7, and a 1 in each bit 0-6 
that you want to change.) 

Line 1030 puts a $FF in the DDRA, 
programming all eight lines of port A 
as outputs. Line 1040 writes $0F to 
DDRB, making the lower four lines 
(PB0-PB3) outputs and the upper 
four (which are not used in this oper- 
ation) inputs. Line 1050 then writes 
$01 to output register B (ORB), caus- 
ing line PBO to apply the hold signal 
to the clock. 



124 Microcomputing, August 1981 



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• See List of Advertisers on page 194 



Microcomputing, August 1981 125 



40 
50 
60 

Z° 
80 

90 

99 : 

100 

102 

110 

120 

130 

200 

210 

220 

240 

250 

280 

282 

284 

286 

290 

300 

320 

330 

340 

350 

360 

370 

380 

390 

400 

500 

510 

520 

530 

540 

550 

560 



REM ************************ 
REM * * 

REK * 6522 T2 TIMER DEMO * 
REM * D.GOSS 11 OCT 80 * 
REM * * 

REM ************************ 

SLOT = 4 

BA = 49280 + SLOT * 16: REM BASE I/O ADDR 
IR = 768: REM BASE ADDR * INTERRUPT ROUTINE 
IV = 1022: REM BAwE ADL'k, INTERRUPT VECTOR 
EI = 800 : REM BASC ADUR, ENAB iRQ 



DATA 

FOR I 

POKE 

POKE 

POKE 

HOME 

PRINT 

PRINT 

PRINT 

INPUT 

T = 

TH = 
POKE 
POKE 
POKE 
POKE 
POKE 
POKE 
POKE 
POKE 
POKE 
POKE 
CALL 
PRINT 
PRINT 
PRINT 
END 



32r53r255» lu; i 127 ■ 
= o to a: READ D 
IR + 



141 ,205,192*64 



IV, 

IV + 



i,d: nea 



REM LOAD INTERRUPT ROUTINE 



REM SE1 INTERRUPT VEC I OR 



l,3i 
VTAB 3 

THIS PROGRAM DEMUNSi RAILS OPERATION OF" 
PRINT "THE 12 1 InL»\ Bf SETTING AN ALARM TIMER. 
PRINT 
ENTER TIME IN oEC v. 6j> MAa ) : ' Jl 
INT (T * 1024 ) 
INT (T / 25o;:iL = 1 - TH * 256 



BA 

BA 

BA 

BA, 

BA 

BA 

BA 

BA 



3,24u 

1,240: REM CLK ADDR = *F 



+ 2,15 

2*. REM SEi READ CmD 

+ 11,32: REM SEI T2 PUSLE COUN 1 MODE 

+ 14,160: REM ENABLE 12 INI LKhUr 1 

+ 8,TL: REM SEI T2 LU 

+ 9,th: REM SE i T^ HI 
EI ,38 
El + 1,96 
Ei: REM ENABLE 

PRINT 



Ow.OJ ii\ ILRKbi- . b 



" TONE WILL SOUND UHEN TIME EXPIRE^" 



Listing 4. 6522 T2 Timer Demo. 



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Note that at this point we should al- 
low a minimum delay of 150 us be- 
fore writing data to the clock. The ex- 
ecution of BASIC is slow enough, 
however, that a separate delay state- 
ment is not required. Lines 1060 
through 1320, in conjunction with 
the subroutine at line 2000, set the 
clock by writing one digit at a time. 

The "POKE RA, -" statements set 
the appropriate clock address and 
data in output register A (ORA), fol- 
lowing which the subroutine at 2000 
loads the data into the clock by turn- 
ing the write command on and then 
off. After all the data has been load- 
ed, the program returns to line 690, 
which calls the machine-language 
Read Clock routine to read the clock 
and display the results for verifica- 
tion. Upon return the hold is released, 
allowing the clock to run normally. 

Reading the Clock 

The procedure for reading the clock 
is illustrated by the Read Clock rou- 
tine (Listing 2), which prints the time 
and/or date on the screen or printer at 
the cursor location. Note that the rou- 
tine starts at $9858 (39000), which is 
in the DOS 3.2 buffer space for a 48K 
system. It will be safe there assuming 
that MAXFILES is three (the normal 
value) and that there are not more 
than two files open at one time. Also 
note that the routine is written for 
slot 4. If you put your card in a differ- 
ent slot you will need to change the 
card address references. 

It may be easier to understand the 
card's operation from the assembly 
listing because it exposes more detail 
than the BASIC listing does. The pro- 
cedure is very much like that used to 
set the clock, except that DDRA is 
programmed so that lines PA0-PA3 
are inputs rather than outputs. The 
time and date are read out one digit at 
a time, converted to ASCII, and out- 
put using the monitor's COUT sub- 
routine. 

On exit the clock address is set to 
$F, which is the address required to 
enable the timing pulse outputs. Note 
that the routine preserves the clock 
command status by saving the con- 
tents of output register B, and then re- 
storing it prior to exit. The status of 
the read, write, hold and chip select 
lines will therefore be left unchanged. 

A Clock Demonstration 

The Clock Demo routine (Listing 3) 
is a short machine-language program 
which demonstrates the clock opera- 
tion and the interrupt capability. The 



126 Microcomputing, August 1981 



circuit is programmed to generate an 
interrupt once/second, and on each 
interrupt the time and date are dis- 
played using the Read Clock routine. 
Pressing any key will terminate the 
program and return control to the 
monitor. 

The demonstration routine starts 
by setting the 6522 to enable the 
once/second interrupt, then sets the 
interrupt vector in $3FE and $3FF. 

The circuit is inexpensive and 

relatively simple to construct, 

but offers a good measure 

of capability. 



The interrupt routine itself starts at 
$99A1. It is a simplified routine in 
that only the once/second interrupt is 
expected. If multiple interrupts were 
enabled, it would be necessary to 
read the IFR and shift it right or left to 
determine which interrupt had oc- 
curred before taking further action. It 
would also be possible in that case for 
two or more interrupt flags to be set 
at the same time. Your program 
would then have to process them 
sequentially in accordance with 
whatever priority you set. 

Using the Timers 

The last program, Listing 4, is an 
Applesoft program that gives a sim- 
ple demonstration of the 6522 timer 
capability. The program uses the T2 
timer in the pulse counting mode, 
counting pulses from the 1024 Hz 
output of the 5832. The timer is set 
with a time value entered from the 
keyboard, and when the selected 
time interval expires, the timer gen- 
erates an interrupt. The interrupt 
routine, which is poked into memory 
beginning at $300, beeps the speaker 
and then clears the interrupt flag by 
writing directly to the interrupt flag 
register. 

Summary 

The circuit described here is inex- 
pensive and relatively simple to con- 
struct, but offers a good measure of 
capability. The programming exam- 
ples only begin to explore potential 
applications. To fully understand all 
of the available operating modes, par- 
ticularly of the timers, you should 
have a copy of the specifications on 
the 6522. The one that I have been us- 
ing is published by Synertek, PO Box 
552, Santa Clara, CA 95052. ■ 



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Microcomputing, August 1981 127 



Here's a cheap mod that lets you hear programs as you load the tape. 



The Ten Cent Fix 



By Don Lancaster 



A ten-cent modification to a cas- 
sette recorder can dramatically 
improve its convenience and reliabil- 
ity as an I/O device for your com- 
puter. 

Simply take the recorder apart and 
find the cassette's ear jack. Add a 470 
ohm, l A watt resistor. Connect this re- 
sistor to the contacts on the ear jack, 
so that the speaker is driven through 
the resistor when something is plugg- 
ed into the ear jack and is driven at 
normal volume when something is 
not (Fig. 1). 

When you load a tape, the speaker 
will softly play back the tones as they 
go into your micro. This immediately 
tells you when your tone codes start 
and stop. 

Better yet, with some practice, 
you'll be able to determine proper 
volume or tone settings and whether 
or not a tape is bad. 

For some micros, including the Ap- 
ple II, this "list en-quiet ly-to-the- 
tones-going-in" route lets you start 
the tone before you hit RETURN. 
This increases your chance of a good 
load, since it eliminates any glitches 
and pops before the tone starts. 



AMPLIFIER 



"EAR" JACK f 

v f r 



AMPLIFIER 



^— SPEAKER 

^CHASSIS 




(a) BFFORl 



(b) Mrre* 



This idea only works on micros that 
have a long "preamble" or "locking 
tone" ahead of the actual data that's 
to be loaded. 

Some Other Hints 

Some tape recorders are fussy 
about how you connect them. A few 
demand a low resistance output load, 
such as the speaker, a headphone or a 
100 ohm resistor. Disconnect these, 
and the internal amplifier feedback 
may give you a distorted, unusable 
output. Unless you know your re- 
corder very well, it pays to put a 100 



switch that selects one or the other. 
Be sure to switch ground as well as 
the hot leads. 

It's also a good idea to erase a tape 
completely before reuse. Should the 
old data start before you begin the 
new data, you'll get a glitch and an er- 
ror message on the preamble almost 
every time. 

Never record an "improved" pro- 
gram over the previous version. If 
anything goes wrong, you'll lose both 
old and new versions and have to re- 
set to zero. Instead, use two tapes and 
alternate between them as you make 



With some practice, you'll be able 

to determine proper volume or tone settings 

and whether or not a tape is bad. 



Fig. 1. Adding a resistor to the ear jack lets you 
softly hear programs as they load. 



ohm load on your the recorder's in- 
put line. Often, just the "quiet listen" 
resistor you added will do the trick. 
Other recorders are intolerant of a 
ground loop between ear output and 
auxiliary input. This can put extra 
hum and noise into your programs. 
In a few cheap recorders, connecting 
both at once can even short out the 
amplifier electronics. So, again, un- 
less you know your recorder, it is un- 
wise to connect both the ear and aux- 
iliary cables at the same time. You 
can get around this by plugging in on- 
ly one at a time, or you can add a 



improvements. Label your better im- 
proved versions. This way, if you 
have any problems, you only lose the 
most recent version, rather than ev- 
erything you have done so far. 

As a final hint, rewind your tapes 
before, rather than after, you use 
them. In this way, you can store your 
tapes with much less tension on them 
and prevent stretching. ■ 



Don Lancaster 
Synergetics 



128 Microcomputing, August 1981 



No matter how active or slow the trading is, this program will keep your portfolio up to date. Part 2. 



Put Your Micro 
On Wall Street 



TIMEGAIN is a short program 
which helps evaluate one or more 
stock portfolios over a specified peri- 
od of time— a week, month, whatever. 
As written, it must be used with 
PORTVAL, described last month (but 
reprinted here), as all the data used is 
stored in PORTVAL and passed to 
TIMEGAIN with the Microsoft disk 
BASIC CHAIN command. (See "Put 
Your Micro on Wall Street,' Micro- 
computing, July 1981, p. 126.) You 
could add READ-DATA lines to make 
the program stand alone, but the idea 



By Dex Hart 

is to make portfolio updating easy— 
because if it isn't easy you probably 
won't do it (I'm assuming the rest of 
the world is as lazy as I am). I use 
these programs to follow several 
portfolios, and, while short and sim- 
ple, they work. 

The intent is twofold: to offer pro- 
grams genuinely useful in portfolio 
bookkeeping and management and to 
demonstrate some aspects of Micro- 
soft BASIC that appear to me to have 
been somewhat neglected. In last 
month's article the emphasis was on 



PORTVAL.TWO. 




10 REM ***** "PORTVAL.TWO" ****** 




20 CLEAR 




30 N=5 




40 IF N<=10 GOTO 60 




50 DIM AS(N) f D$(N],S[N),C(N),P(N) t P1[Nl,V(N) f D[N] f G(N) 




60 RESTORE 




70 FOR 1=1 TO N 




80 READ A$(I),D$(I),S(I),C(I) 




90 NEXT I 




100 DATA Carlisle, 29Sep80, 160, 9991 




110 DATA Crown Co rk,18Mar71 ,100,2231 




120 DATA Humana," 7Mar77", 900, 4900 




130 DATA Kysor,18Dec69,200,2758 




140 DATA Travelers, " 2Dec68", 100, 3511 




160 FOR 1=1 TO N 




170 READ P(I) 




180 NEXT I 




181 READ D1 $ 'date of "new" prices — type w/o commas as item n+1 




182 FOR 1=1 TO N 




183 READ PKI) 'To update, input new prices ABOVE line 188; 




184 NEXT I 'keep old prices on 188, delete 190, then RENUM 




185 READ D2$ 'date of "old" prices 




188 DATA 85,32,74.8,10.4,39.3,21 Jen 81 




190 DATA 84.0,28.4,71.4,10.6,38.9,30 Dec 80 




194 PRINT "Complete this run before chaining TIMEGAIN." 




195 INPUT "Want to run TIMEGAIN? YES enter 1; NO hit return ",W 




196 IF W=1 THEN 197 ELSE 200 




197 COMMON N,A$U,SU,PU,P1(),D1$,D2$ 




198 CHAIN "TIMEGAIN" 




200 T1=0:T2=0:T3=0:T4=0 




210 FOR 1=1 TO N 




220 V(I)=S(I)*P(I) 




230 D(I)=V(I)-C(I) 




240 G(I)=100*D(I)/C(I) 




250 T1=T1+C(I) 




260 T2=T2+V(I) 




270 T3=T3+D(I) 




280 T4=100*T3/T1 




290 NEXT I 




300 PRINT CHRSM2) 'clear screen 




310 PRINT" 'PORTVAL.TWO' Portfolio Valuation prices es of ";D1$ 




320 PRINT 




330 PRINT" Stock Date Shares Cost Price Value Diff %Gain 


ii 


340 PRINT 




350 FOR 1=1 TO N . 




360 PRINT USING"## ";I; ( 


More » 



PRINT USING (and LPRINT USING) 
along with some elementary field 
arithmetic, especially how column 
totaling works. The second program, 
TIMEGAIN, chains to the original 
program and thus greatly simplifies 
data inputting. Note that CHAIN and 
COMMON are new to Microsoft BA- 
SIC as of version 5.0. 

Target Group 

I'm aiming this at those not-yet-ex- 
pert BASIC programmers, a group in 
which I include myself. But I have 
learned some aspects of the language 
well, because I had to, and that 
limited area of acquired knowledge is 
what I'm sharing with you. You don't 
have to be a heavyweight investor to 
benefit from learning how these pro- 
grams work, as the applications have 
wide general application. 

I call TIMEGAIN a universal pro- 
gram, because it will work with any 
number of separate portfolio valua- 
tion programs and never has to be 
changed, updated or loaded with 
data. 

PORTVAL Revisions 

The revisions to last month's PORT- 
VAL are slight. To distinguish the 
version with the CHAIN statement, 
I've called it PORTVAL.TWO. There 
are four revised lines and ten new 
ones. Lines 10, 310 and 550 are re- 
vised to reflect the program name 
change. Line 50 is revised to dimen- 
sion for PI, the 'old" share prices, 
since we now need stock prices for 
two different dates. New lines 182, 
183 and 184 loop to read the old 
prices left in place as extra DATA. 
Note the remarks on the latter two of 



Dex Hart (9414 SW 142 St., Miami, FL 331 76) is a 
widely published boating writer. 



130 Microcomputing, August 1981 



these lines; I have not renumbered so 
as to avoid disturbing the original 
PORTVAL numbers, but when you 
do you will have to revise the line 
number references in these remarks. 
There's an extra nonlooped READ 
line for the date of the "old" prices, 
D2$, since we will need both dates in 
TIMEGAIN to fully identify the span 
of time involved. Each date is listed 
as the final (n+1) item following n 
prices. If a large number of stocks is 
involved, and more than one DATA 
line is needed for each set of prices, 
the date also serves as a nice visual 
break between the two series of 
prices. Just remember to add the 
newest date as the final entry when- 
ever entering prices. (The newest 
prices are on line 188; the former 
prices on 190.) The CHAIN-related 
commands are new lines 194-198. 

TIMEGAIN has only 51 lines, but 
part of its compactness is in the meth- 
od of writing PRINT USING. Com- 
pare the PRINT USING sections of 
PORTVAL.TWO and TIMEGAIN. 
Recognize that they do the same 
thing— format a whole line of stripg 
and numerical data, controlling loca- 
tion, decimal places and rounding. It 
is an extremely useful command sys- 
tem. Table 1 of last month's article 
lists the variables. Add to that PI, 
which is used in TIMEGAIN for 
share prices predating the current 
prices. 

What we are doing in TIMEGAIN 
is to multiply the older price by the 
number of shares to get the "old" to- 
tal cost, C; we then multiply the new 
prices, P, by the number of shares to 
get the current value of each stock, V. 
The dollar difference, D, is again V 
minus C, and the gain, G, is again the 
percentage gain or loss. 

Program Differences 

The difference is that while PORT- 
VAL does its arithmetic on each stock 
from the purchase date of that stock, 
TIMEGAIN uses start and end dates 
which are the same for each stock. A 
glance at the sample runs of the two 
programs illustrates the difference 
and also shows how useful TIME- 
GAIN is. Last month's PORTVAL 
was as of Dec. 31, 1980. This month's 
PORTVAL.TWO is three weeks later, 
as of Jan. 21, 1981. The specific num- 
bers are not greatly different be- 
tween the two runs, and it is not im- 
mediately obvious where the greatest 
changes took place across that three 
weeks (the Dec. 31 %Gain, for exam- 
ple, was in order: 34.5, 27.3, 1211.4, 



Listing continued. 












370 


PRINT USING "\ 


\ H ;A$(I); 










380 


PRINT USING "\ \ 


";D$(D; 










390 


PRINT USING"### "; 


S(I); 










400 


PRINT USING"##### 


"iCCXli 










410 


PRINT USING"##.# 


";P(D; 










420 


PRINT USING"##### 


";V(IJ; 










430 


PRINT USING "##### 


";D(D; 










440 


PRINT USING"####.#" 


;G(I) 










450 


NEXT I 












460 


PRINT"*****************************************************************" 


470 


PRINT "Totals"; 












480 


PRINT TAB (29) USING" 


###### 


###### 


";T1; 


T2; 




490 


PRINT USING"##### 


###.#" ;T3;T4 










500 


PRINT 












510 


INPUT "Hard copy?— 


YES enter 1 (p 


rinter on 


!)— NO 


hit RETURN ",J 




520 


IF .|=1 THEN 550 ELSE 540 










530 


GOTO 550 












540 


END 












550 


LPR I NT "'PORTVAL. TWO 




io Valuation... 


.Prices es of "; 


D1$ 


560 


LPRINT 












570 


LPRINT" Stock 


Dete Shares Cost 


Price 


Value Diff 


%Gain" 


580 


LPRINT 












590 


FOR 1=1 TO N 












600 


LPRINT USING"## ";I 


• 
f 










610 


LPRINT USING"\ 


\ ";A$(D; 










620 


LPRINT USING"\ 


\ ";D$(D; 










630 


LPRINT USING"### " 


;S(I); 










640 


LPRINT USING"##### 


";C(D; 










650 


LPRINT USI.NG"##.# 


"jPCIJl 










660 


LPRINT USING"##### 


"fVIIli 










670 


LPRINT USING"##### 


";D(D; 










680 


LPRINT USING"####.# 


";G(D 










690 


NEXT I 












700 


LPRIN j "******** ***********************************^* ************ *******" 


710 


LPRlNT"Totals"; 












720 


LPRINT TAB (28) USING 


" ###### 


###### 


";T1 


?T2; 




730 


LPRINT USING"##### 


###.#" ;T3;T4 










740 


GOTO 540 













•PORTVAL.TWO'. 




Vsluetion. . . . 


.Prices 


es of 21 


Jen 81 


Stock 


Dete Shores Cost 


Price 


Value 


Diff 


XGein 


1 Carlisle 


29Sep80 160 


9991 


85.0 


13600 


3609 


36.1 


2 Crown Cork 


1QMer71 100 


2231 


32.0 


3200 


969 


43.4 


3 Humana 


7Mar77 900 


4900 


74.8 


67320 


62420 


1273.9 


4 Kysor 


18Dec69 200 


2758 


10.4 


2080 


-678 


-24.6 


5 Travelers 


2Dec68 100 


3511 


39.3 


3930 


419 


11.9 


************************************ **************************** 


Tote Is 




23391 




90130 


66739 


285.3 




PORTVAL.TWO 


sample 


run. 







-23.1, 10.8. Total gain, 270.0 per- 
cent). 

But look at TIMEGAIN, which 
shows the gain only for that three- 
week period: Crown Cork had the 
largest move, three times that of 
Humana (although the Humana per- 
centage gain has the most effect on 
the total gain, because it represents 
three-quarters of our arbitrary port- 
folio—a fact easily apparent since we 
have added a new column, percent of 
portfolio, to TIMEGAIN). 

I keep a notebook titled, not sur- 
prisingly, "Portfolio." For any specif- 
ic portfolio, I file each hard copy of 
PORTVAL, making notes on these 
copies of any transactions or items of 
special interest. I will occasionally 
run TIMEGAIN, normally as of the 



last trading day of each month. I re- 
ceive an overall portfolio valuation 
from either program, but one shows 
my overall progress (not always en- 
couraging), the other my current 
progress (also not always encourag- 
ing). But good news or not, you need 
to know how you're doing. If there's 
a problem, you won't solve it with 
your head in the sand. The main 
point: the two programs give differ- 
ent information— and both are useful. 

How TIMEGAIN and 
Chaining Work 

You don't want to load two sets of 
prices at a time; it doubles the work. 
So what you do is just leave the for- 
mer prices in PORTVAL, although 
you won't use them there. At the next 



Microcomputing, August 1981 131 



update, you input the new prices be- 
fore them (lower line number), and 
get rid of the really old prices by 
blanking the appropriate lines. This 
all takes place in PORTVAL. The re- 
marks in lines 183 and 184 should 
make the process clear. The result is 
to always maintain two sets of prices 
of DATA, the newest first. 

If you want to leave a particular set 
of prices in, such as the end-of-the- 
former- month prices, you don't do 
the renumbering business— just in- 
put the new prices on the new-price 
data lines, thereby (in this short port- 
folio example, on line 188) erasing 
the "intermediate" prices. When you 
want to run TIMEGAIN in the future, 
the start-period prices will be waiting 
for you (in this case, on PORTVAL 
line 190). 

The whole idea is to never have to 
input more than a single set of prices 
at one time. It works just fine. There 
is a reminder in PORTVAL.TWO to 
finish its run first. That's because 
once you chain TIMEGAIN, you've 
lost PORTVAL. You could chain 
back, but why? Finish PORTVAL, 
print a hard copy if you choose, then 



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run PORTVAL again and this time 
branch to the CHAIN operation 
when asked. TIMEGAIN will print to 
the screen and also offer you the 
hard-copy election. 

If you want to pass all the variables, 
you just add a comma and the word 
ALL after CHAIN, without a COM- 
MON statement. That seems waste- 
ful so you just pass along the ones you 
need by using a COMMON state- 
ment (line 197) just before CHAIN. 
The variables specified will thus be 
common to each program. Note the 
format: Array variables are identified 
by a pair of empty parentheses. Note 
also that you only need to dimension 
the new variables you are calculating 
(see line 20)— not the ones being 
passed from the source program. 

Inside TIMEGAIN, the new col- 
umn, percent of portfolio, is identi- 
fied by R. The "total" variables are 
basically the same, except that a fifth 
total has been added. T3 now be- 
comes the "%Port" total— always 
100 percent— stuck in the middle of 
the group. 

So you transfer all the needed vari- 
ables from PORTVAL: n, stock name, 
number of shares, new and old share 
prices and both dates. Move things 
about a bit, and you'll have a table 
full of new data. 

Again I remind you that "PRINT 
CHR$(12)" is how I clear screen on 
my Superbrain. Your machine is 
probably different. "CLS" is a popu- 
lar command. Or you might use a dif- 



ferent CHR$ number. 

Random Thoughts 

Some final comments on documen- 
tation. We all know that the general 
level is bad. I believe Digital Re- 
search writes theirs in Chinese, but 
they recently sent me a mailing not- 
ing the existence of two CP/M books, 
Rodnay Zaks' The CP/M Handbook 
and Using CP/M by Judi Fernandez 
and Ruth Ashley. While Digital Re- 
search stops short of recommending 
these books, I don't. I have both and 
need both. Each covers material not 
covered in the other. 

Microsoft's documentation is some- 
what better than Digital Research's, 
but is far from prize-winning. Longer 
examples, a few more words and 
more clarity would make things so 
much easier. I haven't found a specif- 
ic Microsoft book yet, although there 
is one aimed at Radio Shack' s version 
of Microsoft. That's why I spent 
some time explaining PRINT USING, 
since it is difficult to figure out from 
documentation alone. I had to see a 
program using it. By outlining the 
full-line formatting function, perhaps 
I have done the same for you. 

One final note: I never could figure 
out what WHILE- WEND meant. That 
is, I knew the WHILE meant "as long 
as," but WEND means to turn or pro- 
ceed, right? You wend your way 
through? No clues from Microsoft 
(they don't answer letters either— at 
least not from me). Fortunately, I 





TIMEGAIN program in Microsoft BASIC. 






10 REM ***** TIMEGAIN 


***** Universe 


L Chain/Common 


Program 






20 DIM C(N),V(N),R(N) 


D(N),G(N) 










30 T1=0:T2=0:T3=0:T4=0:T5=0 










40 FOR 1=1 TO N 












50 C(I)=S(I)*P1(I} 












60 V(I)=S(IJ*P(I) 












70 D(I)=V[I)-C{I) 












80 G(I)=100*D(I)/C(I) 












90 T1=T1+C(I) 












100 T2=T2+V(I) 












110 T4=T4+D(I) 












120 T5=100*T4/T1 












130 NEXT I 












140 FOR 1=1 TO N 












150 R(I)=100*V(I)/T2 












160 T3=T3+R(I) 












170 NEXT I 












180 PRINT CHR$(12) 












190 PRINT"' TIMEGAIN' Stock Value Change Over ime- 


-New prices ss 


of ";D1$ 




200 PRINT TAB (42) "Old 


prices ss of " 


;D2$ 








210 PRINT 












220 PRINT" 


Old 


Total New 


Current" 






230 PRINT" Stock 


Shores Price 


Cost Price 


Velue XPort Diff 


%Gein" 


240 PRINT 












250 FOR 1=1 TO N 












260 PRINT USING"## \ 


\ #### ###.# 


";I;A$(I);S(I) 


;P1(I);C(I) 


I 


270 PRINT USING"###.# 


###### ###.# 


###### ####.#";P(I);V(I) 


;R(I);D(I); 


BCD 


280 NEXT I 












290 PRINT" 










n 


300 PRINT "Totals"; 












310 PRINT TAB (27) USING "###### 


###### ";T1 


;T2; 






320 PRINT USING"###.# 
330 PRINT 


###### #### 


.#";T3;T4;T5 






G vfor £- — * 



132 Microcomputing, August 1981 



came across a FORTRAN book and 
found the answer. The FORTRAN 
commands are WHILE and END 
WHILE. So simple when you see it— 
WEND is WhilEND. Why couldn't 
Microsoft have mentioned that? 

Then there is the explanatory ex- 
ample Microsoft used. What kind of 
BASIC statements are WHILE FLIPS 
and FLIPS = 0? Long variable names? 
Something to do with sorting, a par- 
ticular weak point with me— but 
then, I have no need to sort. 

I'll find out someday, from some- 
where or someone. And after all, 
would this whole business be so fas- 
cinating if it was without challenge? 

For the Future 

As soon as I dig out a full historical 
listing of the Consumer Price Index 
(CPI), I plan to work up another pro- 
gram, also chained to PORTVAL, 
which will apply the index to stock 
values, comparing how a portfolio 
has done in current dollars to how it 
has done in deflated dollars. The re- 
sults will once more probably be dis- 
couraging, but better to know than to 
ignore. Sure hope I don't need FLIPS 
to make it work.H 



Listing continued. 

340 INPUT "Hard copy?— YES enter 1 (printer on!)— NO hit RETURN ",J 

350 IF J=1 THEN 370 ELSE 360 

360 END 

370 LPRINT"' TIMEGAIN' Stock Value Change Over Time— New prices as of ";D1$ 

380 LPRINT TAB(42)"0ld prices as of ";D2$ 

390 LPRINT 

400 LPRINT" OLd TotaL New Current" 

410 LPRINT" Stock Shares Price Cost Price Velue %Port Diff XGain" 

420 LPRINT 

430 FOR 1=1 TO N 

440 LPRINT USING"## \ \ #### ###.# ###### ";I ;A$(I) ;S(I ) ;P1 (I) ;CtI) ; 

450 LPRINT USING "###.# ###### ###.# ###### ####.#»;P{I) ;V(I) ;R(I J ;D(I J ;GII) 

460 NEXT I 

470 LPRINT"**************************************************»********************" 

480 LPRINT"Totals"; 

490 LPRINT TAB (27) USING "###### ###### ";T1;T2; 

500 LPRINT USING"###.# ###### ####.#";T3;T4;T5 

510 GOTO 360 



'TIMEGAIN* Stock Value Change Over Time — New prices es of 21 Jan 81 

Old prices as of 30 Dec 80 





Old 


Total 


New 


Current 








Stock Shares 


Price 


Cost 


Price 


Value 


%Port 


Diff 


%Gain 


1 Carlisle 160 


84.0 


13440 


85.0 


13600 


15.1 


160 


1.2 


2 Crown Cork 100 


28.4 


2840 


32.0 


3200 


3.6 


360 


12.7 


3 Humane 900 


71.4 


64260 


74.8 


67320 


74.7 


3060 


4.S 


4 Kysor 200 


10.6 


2120 


10.4 


2080 


2,3 


-40 


-1.9 


5 Trsvelers 100 


38.9 


3890 


39.3 


3930 


4.4 


40 


1.0 



*********************************************************************** 
Totals 86550 90130 100.0 3580 4.1 

TIMEGAIN sample run. 



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Microcomputing, August 1981 133 




This program gives a lift to aerospace engineering and shows that micros 
can save time and money in high-technology endeavors. 



Most major aerospace missile sys- 
tem contractors have an ad- 
vanced engineering concepts or pre- 
liminary design group whose pur- 
pose is to analyze the defense market- 
ing environment and define new or 
modified weapon systems. They of- 
ten must develop performance re- 
quirements of conceptual missile de- 
signs or characterize the abilities of 
existing missile systems used in new 
applications. 

Until recently, the techniques to do 
this have been limited. Laborious 
hand calculations and pocket calcula- 
tors cost time and accuracy, since 
many simplifying assumptions had to 
be made to reduce a problem to man- 
ageable size. 

Existing missile simulation com- 
puter programs running on corporate 
mainframe systems, such as a CDC 
7600 or IBM System 370, also pre- 
sented problems. The data is used 
mainly to show the feasibility of a 
certain missile system concept, 
which requires that the system be 
simulated in enough detail for the re- 
sults to be valid, but not in such detail 
that every nut and bolt is defined. 
Thus, full-blown mainframe simula- 
tions typically have far more capabil- 
ity than necessary. Also, the cost of 
generating data is very important, 
and cranking out a lot of numbers at a 
rate of $30 per CPU-second can 
quickly deplete an annual computer 
budget. 

Enter the Microcomputer 

A missile preliminary design group 
can now own a dedicated computer 



TRS-80 Launchpad 



By Terry L. Sunday 



that will support its engineering anal- 
yses. Ready machine access and 
straightforward programming en- 
courage use of such a computer in a 
wide variety of tasks. And best of all, 
after the initial system purchase, 
mountains of data can be generated 
at no cost to the user. 

The program described here is for a 
TRS-80 Model I Level II, with 32K, 
two 5-1/4-inch disk drive units, a line 
printer and a power line filter assem- 
bly. The power line filter was neces- 
sary because of the system's sensitiv- 
ity to line fluctuations, which was 
particularly apparent in the morning 
and afternoon hours when most em- 
ployees arrived at or left the plant. 
The program is written in Level II 
BASIC and occupies about 10,500 
bytes of memory. 

The Program 

The program is a two-degree-of- 
freedom (pitch-plane) missile trajec- 
tory simulation, and simulates the 
flight of a missile following launch ei- 
ther from the ground or from an air- 
craft. A completely arbitrary missile 
configuration may be used, so the 
same program is useful for many dif- 
ferent analyses. 

The missile may or may not have a 
rocket motor, and if it does, the mo- 
tor is characterized by arbitrary 
thrust, ignition time, burn time and 
propellant weight. Of course, the mo- 
tor parameters must be internally 
consistent. The missile configuration 
itself is defined by weight, size and 
aerodynamic characteristics. A flat, 
nonrotating earth is assumed, as well 
as an exponential atmosphere model. 
The flat earth assumption has proven 



to be quite acceptable for the short 
ranges involved in all program utili- 
zation to date. 

The program output consists of a 
tabular listing of missile range, alti- 
tude, flight path angle and velocity, 
all presented as a function of time. 
This output can be selected to appear 
either on the CRT display or in hard- 
copy form on the line printer. 

Listing 1 is the current version of 
the program, which will be discussed 
in detail later. Table 1 shows the in- 
put parameters required by the pro- 
gram. Note that the input parameters 
are divided for convenience into mis- 
sile configuration data, initial condi- 
tions, control parameters and aerody- 
namic characteristics. The aerody- 
namic data required is expressed as 
axial and normal force coefficients, 
as a function of Mach number and 
angle of attack, in missile body axes. 
Provisions are included to use both 
power on (rocket motor burning) and 
power off (rocket motor not burning) 
data sets. The differences between 
power-on and power-off aerodynam- 
ic data may be important in some ap- 
plications. An option lets you use on- 
ly power-off data, a simplification 
that may frequently be employed 
without introducing significant error. 
In that case, a data flag is set which 
bypasses the requirement to provide 
power-on data. 

Details of the program structure 
may be seen by examining Listing 1. 
Lines 60 through 90 establish the ar- 
ray dimensions and assign values to 

Terry L. Sunday (3005 Devils Tower, El Paso, TX 
79904} is a staff engineer with Martin Marietta 
Aerospace. 



134 Microcomputing, August 1981 



various pnysicai and atmospheric 
model constants. Lines 110 through 
590 contain the data input routine. 

In the present version, a separate 
disk file, using DATA statements and 
with its first line number greater than 
the highest simulation program line 
number (5000 is typically used), must 
be established. The simulation pro- 
gram is first loaded into the comput- 
er, and the MERGE command is then 
used to attach the data file to the end 
of the program. This technique lets 
you set up multiple data sets, each 
representing a different missile con- 
figuration. Note the extensive use of 
integer array subscripts, as identified 
by the % character, to help speed up 
program execution. 

Lines 530 through 590 let you 
change any of the data items before 
running the program, or between the 
runs in a series. Lines 620 through 
650 permit the output option— either 
CRT or line printer— to be chosen, 
and lines 660 through 690 let you in- 
put a descriptive alphanumeric title 
that will appear as a heading on the 
printout. Lines 700 through 890 set 
up the initial values for various pa- 
rameters used in the integration loop. 

The actual integration loop runs 
from line 940 to line 2170. It is within 
this loop that all of the missile trajec- 
tory computations are performed. A 
trapezoidal integration scheme is 
used, with the time interval for inte- 
gration steps defined by the input 
variable DT. A value of .5 second for 
DT is usually adequate. 

Lines 970 through 1040 establish 
the exponential atmosphere parame- 
ters as a function of missile altitude, 
and determine the instantaneous 
missile Mach number for entry into 
the aerodynamic data tables. Lines 
1050 through 1290 contain a routine 
which modifies the computation in- 
terval to force an integration to be 
performed at the discontinuities rep- 
resented by rocket motor ignition or 
burnout, which need not occur exact- 
ly coincident with a normal integra- 
tion step. A forced line print also oc- 
curs at these times. 

The heart of the integration loop 
lies between lines 1320 and 1780. 
Here the forces acting on the missile 
are computed on each pass through 
the loop. This portion of the program 
is divided into two segments— the re- 
gion from line 1340 to line 1550 is 
used when the rocket motor is burn- 
ing, and the region from line 1560 to 
line 1780 is used when the motor is 



not burning. Each segment uses the 
appropriate table of power-on or 
power-off aerodynamic data, and if 
no power-on data is provided, the 
portion from line 1340 to line 1550 is 
bypassed. In either case, a double lin- 
ear interpolation on both Mach num- 
ber and angle of attack is used to pro- 
duce as a final result the net drag and 
lift forces to which the missile re- 
sponds. These forces are then used to 
determine missile longitudinal and 
lateral accelerations in lines 1790 and 
1800, and then to update the missile 
velocity and position in lines 1810 
through 1910. These are then used as 
starting conditions for the next pass 
through the loop. 

The routine between lines 1920 
and 2110 forces a line print at rocket 
motor ignition and burnout. If the 
line printer output option is selected, 
these lines are identified by the word 
"ignition" or "burnout" printed to 
the right side of the basic tabular out- 
put. On the CRT output, no such 
identifier is presented. 

Lines 2120 and 2130 check to see 
whether the stopping conditions— ei- 
ther maximum time or cutoff altitude 
—are satisfied, in which case the pro- 
gram transfers to one of two termina- 



tion routines. Lines 2210 through 
2540 contain the output logic. This 
routine prints identifying headings 
on the columns of output data, condi- 
tions the missile trajectory data into 
the units employed for output and 
prints the data either on the CRT or 
printer. 

A line of data output is triggered by 
any of the following three conditions: 
an incremental time period defined 
by the input value for print interval, 
PT, is reached; either ignition or 
burnout of the rocket motor occurs; 
or either of the program stopping 
conditions is satisfied. If a stopping 
condition is satisfied, the routine de- 
fined by lines 2550 through 2780 is 
executed, which causes the reason 
for program termination to be print- 
ed, along with the final trajectory 
conditions existing at that point. 

Finally, lines 2790 through 2830 
cause the program to prepare to exe- 
cute again by returning the data 
pointer to the top of the data array, 
and asking the user if he desires to 
make another run. If the response is 
yes, program control transfers back 
to line 580, where any changes to the 
data set are made, and the cycle reini- 
tiates. 



TIME 


RANGE 


ALTITUDE 
<AGL> 


FLIGHT PATH 
ANGLE 


VEL0CITV 


<SEC> 


<KM> 


<FT> 


<DEG> 


<FT/SEC> 


1 





175 


26. 9926 


1834 


1 


. 48781 


974. 742 


26. 0916 


1729. 81 


2 


. 945972 


1695. 84 


25. 1341 


1606. 37 


3 


1. 37628 


2343. 1 


24. 0958 


1500. 48 


4 


1. 78235 


2923. 77 


22. 9745 


1407. 01 


5 


2. 16711 


3443. 73 


21. 7685 


1324. 04 


6 


2. 53284 


3907. 65 


20. 4758 


1249. 35 


7 


2. 83141 


4319. 39 


19. 0933 


1182. 14 


8 


3. 21476 


4682. 63 


17. 6207 


1123. 21 


9 


3. 53485 


5000. 78 


16. 0571 


1872. 82 


10 


3. 84361 


5276. 87 


14. 4053 


1828. 29 


11 


4. 14273 


5513. 4 


12. 6698 


991. 078 


12 


4. 4337 


5712. 4 


10. 856 


959. 446 


13 


4. 71764 


5875. 39 


3. 96993 


932. 071 


14 


4. 99531 


6003. 49 


7. 0172 


907. 941 


15 


5. 2673 


6097. 6 


5. 00297 


836. 679 


16 


5. 53487 


6158. 44 


2. 93282 


868. 008 


17 


5. 79602 


6136. 66 


. 812846 


851. 699 


18 


6. 05345 


6182. 81 


-1. 35034 


837. 431 


13 


6. 30657 


6147. 36 


-3. 54999 


824. 984 


28 


6. 55558 


6088. 78 


-5. 77913 


814. 274 


21 


6. 8O061 


5983. 48 


-8. 03042 


885. 221 


22 


7. 04179 


5855. 89 


-10. 2962 


797. 749 


23 


7. 27924 


5698. 38 


-12. 5686 


791. 783 


24 


7. 51304 


5511. 34 


-14. 8399 


787. 245 


25 


7. 74327 


5295. 16 


-17. 1023 


734. 059 


26 


7. 97 


5058. 21 


-19. 3484 


782. 145 


27 


8. 19326 


4776. 9 


-21. 5711 


781. 423 


28 


3. 4131 


4475. 63 


-23. 7638 


781. 808 


29 


8. 62954 


4146. 81 


-25. 9288 


783. 216 


30 


3. 3426 


3790. 89 


-23. 0367 


785. 557 


31 


9. 0523 


3403. 32 


-30. 107 


788. 743 


32 


9. 25862 


2999. 53 


-32. 128 


792. 685 


33 


9. 46158 


2565. 19 


-34. 0965 


797. 293 


34 


9. 66116 


2105. 66 


-36. 0103 


802. 476 


35 


9. 85734 


1621. 58 


-37. 8677 


808. 146 


36 


10. 0501 


1113. 51 


-39. 6677 


814. 215 


37 


10. 2394 


532. 892 


-41. 4097 


820. 598 


38 


10. 4253 


27. 9639 


-43. 0933 


827. 213 


38. 049 


10. 4343 





-43. 1742 


827. 543 




FLIGHT TERMINATED AT CUTOFF 


ALTITUDE 








Sample run. 







Microcomputing, August 1981 135 



SINGLE BOARD 

COMPUTER 

$49.95 




The MASTER CONTROLLER 
BOARD contains: 

Z-80 Microprocessor: will run 
8080/8085 and Z-80 programs. 
72 - Parallel I/O lines; three 8255s 
Keyboard controller: 8279 
(also can control a 16 digit 
seven segment display) 
12K - EPROM: three sockets for 
2708,2716,2732, 
2K- RAM: 2114s 

8 - Sixteen bit counter timer 
channels: one 8253 and one 
AMD 9513 

2 - Serial I/O ports; one Z-80 SIO 
chip. One port has an RS-232 
interface and connector. 

1 - High speed arithmetic 
processor: AMD 951 1 or 
AMD 9512 

All the I/O chips are memory 
mapped AND I/O mapped. A 
bus expansion connector is 
provided. Can be operated on 
5 volts only. 

All this on one board less than 
nine inches on a side 

Only three LSI chips (Z-80, 8255, 

and EPROM) plus support gates 

and buffers are required for a 

working controller. 

BARE BOARD $49.95 
With documentation. 

MINIMUM KIT $99.95 Includes bare 
board with documentation, one each 
Z-80, 8255, 2708, two 21 14s, and 
support gates and buffers, all socketed. 

MONITOR $39.95 This program allows 
a TTY or CRT to control the MASTER 
CONTROLLER. This program requires 
the minimum kit and monitor parts kit. 
A programmed 2708 is supplied with 
the MONITOR. 

MONITOR PARTS $54.95 

Includes 8253, Z-80 SIO, 1488, 1489, 
and connector. 

POWER SUPPLY $39.95 +5V 1A, -5V 
Y4A.+12V 74A.-12V74A 

POWER SUPPLY $44.95 +5V 2A, other- 
wise same as above. 

Please include $2 postage and handling. 

OEM and dealer inquiries invited. 
VISA and MASTER CARD accepted. 

R.W. ELECTRONICS ..390 

3165 North Clybourn 

Chicago, IL 60618 

(312)248-2480 



NOTE: MAKE SAME AS LAUNCH WEIGHT 



D = MISSILE DIAMETER (INCHES) 

W0 = NISSILE LAUNCH WEIGHT (POUNDS) 

WF = MISSILE BURNOUT OR FINAL WEIGHT (POUNDS) 

FOR UNP0WERED MISSILE. 

BT = MOTOR BURN TIME (SEC) NOTE: MAKE 6 IF NO MOTOR. 

TT = MOTOR AVERAGE (CONSTANT) THRUST (POUNDS) NOTE: MAKE IF NO MOTOR. 

BD = MOTOR IGNITION DELAV AFTER TO (SEC) 



INITIAL CONDITIONS 

H0 = INITIAL ALTITUDE ABOVE GROUND LEVEL (FT) 

R0 =» INITIAL RANGE (KM) 

V0 = INITIAL VEL0CITV (FT/SEC) 

G0 = INITIAL FLIGHT PATH ANGLE (DEGREES) POSITIVE UPWARDS 

T0 = INITIAL TIME (SEC) 

ftG = GROUND ALTITUDE (FT) 



CONTROL PARAMETERS 

TF = MAXIIMUM FLIGHT TIME (SEC) 

HF = CUTOFF ALTITUDE ABOVE GROUND LEVEL (FT) NOTE: CUTOFF WILL OCCUR ONLY IF 

MISSILE IS DESCENDING WHEN REACHING THIS ALTITUDE 

DT = INTEGRATION STEP SIZE (SEC) 

PT = PRINT INTERVAL FOR HARD COPV OR SCREEN DISPLAY (SEC) 

TC(1) = TIME TO INITIATE CONSTANT ANGLE OF ATTACK FLIGHT MODE (SEC) 

TC(2) = TIME TO TERMINATE CONSTANT ANGLE OF ATTACK FLIGHT MODE (SEC) 

AC = CONSTANT ANGLE OF ATTACK (DEGREES) NOTE: TC<1) AND TC(2) MUST BE GREATER 

THAN ZERO 

01/i = POWER ON DATA FLAG: IF 0, NO POWER ON DATA 

IF 1. READ POWER ON DATA 



AERODYNAMIC CHARACTERISTICS 

NHK = NUMBER OF MACH NUMBERS TO BE LOADED (POWER OFF) MAXIMUM 15 

MB = NUMBER OF ANGLES OF ATTACK TO BE LOADED (POWER OFF) MAXIMUM 10 

M(l) TO M(NM/i) = MACH NUMBER VALUES (POWER OFF) 

A(l) TO A(NAX) = ANGLE OF ATTACK VALUES (DEGREES) (POWER OFF) 

CA(M,A) = AXIAL FORCE COEFFICIENT AS A FUNCTION OF MACH NUMBER AND ANGLE OF 

ATTACK (POWER OFF) 

CN(M,A) = NORMAL FORCE COEFFICIENT AS A FUNCTION OF MACH NUMBER AND ANGLE OF 

ATTACK (POWER OFF) 

00/i = NUMBER OF MACH NUMBERS TO BE LOADED (POWER ON) MAXIMUM 15 

AOK = NUMBER OF ANGLES OF ATTACK TO BE LOADED (POWER ON) MAXIMUM 10 

m<p TO M0(OO?O = MACH NUMBER VALUES (POWER ON) 

A0(1) TO A0(AOX) « ANGLE OF ATTACK VALUES (DEGREES) POWER ON 

C0(MO,A0) = AXIAL FORCE COEFFICIENT AS A FUNCTION OF MACH NUMBER AND ANGLE OF 

ATTACK (POWER ON) 

NO (MO, AO) = NORMAL FORCE COEFFICIENT AS A FUNCTION OF MACH NUMBER AND ANGLE OF 

ATTACK (POWER ON) 



Table 1. Variable identification. 



The missile used in the Sample run 
was fired at an angle of 30 degrees 
with an initial velocity of 1834 ft./sec, 
and did not use a rocket motor. The 
configuration actually represents a 
guided artillery projectile which has 
been under development for some 
time, and which was chosen as a test 
case because a large body of perform- 
ance data exists which was used to 
verify the programming of the major 
equations of motion. 

In this example, the projectile fired 
with the specified initial conditions 
hit the ground at a range of 10.43 km 
from the launch point following a bal- 
listic flight of 38.049 seconds dura- 
tion. These values are extremely close 
to those obtained by running a com- 
plete (and costly) six-degree-of-free- 
dom projectile simulation on a Sys- 
tem 370. The value of this TRS-80 
simulation becomes immediately ap- 
parent. 

The program has also to date been 
used to study performance abilities 
for a cannon-launched rocket-pro- 
pelled guided projectile, and for a 
guided missile launched from an air- 



craft under a variety of flight condi- 
tions. 

Modifications 

Several changes may be made in 
the future. An option to simulate con- 
stant angle-of-attack glide is currently 
included in the program, but has not 
been sufficiently checked out to as- 
sure that it is completely debugged. A 
proportional navigation guidance 
scheme to simulate target engage- 
ments would add immeasurably to 
the program, and a simplified mech- 
anization could be incorporated fairly 
easily. 

Another useful modification would 
be to add the third degree of transla- 
tional freedom, cross-range, so the ef- 
fect of crosswinds and other lateral 
disturbances could be assessed. 

Finally, a major effort is anticipat- 
ed to reduce program execution time 
by streamlining the logic wherever 
possible. In its present form, one sec- 
ond of simulated flight requires about 
five seconds of real time with an inte- 
gration interval of 0.5 second, and 



136 Microcomputing, August 1981 



OSI 



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MAXI-PROS has both global and line edit 
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The disk contains a disk manager that con- 
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t^See List of Advertisers on page 194 



Microcomputing, August 1981 137 



this publication 

is available in 
microform 




University Microfilms International 

300 North Zeeb Road 18 Bedford Row 

Dept. P.R. Dept. PR. 

Ann Arbor, Ml 48106 London, WC1R 4EJ 

U.S.A. England 



this is approaching the point wherein 
interactive sessions become too time- 
consuming, due to the wait required 
for execution to be completed. 

During program development, we 
found that the CRT output option 
was used very infrequently, so con- 
sideration is being given to removing 
this option entirely, with a conse- 
quent reduction in computation time 
and much simplification of the com- 
plex output logic. Use of a BASIC 
compiler rather than the existing BA- 
SIC interpreter would greatly im- 
prove execution time. 



Conclusion 

This article has presented a snap- 
shot of a TRS-80 program that has 
proven to be very useful in aerospace 
engineering analyses. Program devel- 
opment is not complete, and prob- 
ably never will be, because there is 
always another option to add. Never- 
theless, even in its present state, it 
has served to demonstrate important 
new capabilities of the current crop 
of microcomputers, and to illustrate 
once again that these machines are 
far more than sophisticated video 
games. ■ 



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TRS 80 is a registered trademark of Radio Shack 



'68' MICRO 



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JOURNAL 

6800-6809-68000 

• The only ALL 68XX Computer Magazine 

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19 
26 
30 
40 
50 
60 
70 
80 
90 

100 

110 
120 
130 
140 
150 
160 
170 
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190 
200 
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296 

200 

310 
220 
220 
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258 
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288 
290 

400 

410 
428 
428 
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760 



Listing 1. Missile Flight Simulation program for the TRS-80 Model I, Level II. 

'"PROGRAM FILESPEC IS TESTS I M VERSION 6/27/80 

'"A TRAJECTORY SIMULATION FOR AIR OR GROUND-LAUNCHED MISSILES 

/ ii 

'"INITIALIZATION 

/ II 

DIM M<15), A(10>, CA<15, 10), CN<15, 10>, TA<2), TC<2>« X<3>* D<4), E<4) 

DIM M0C15), A0<10\C0<15 10), N0C15, it) 

F1=0: G=32. 174: PI=2. 1 415926 : RD=0. 01745229 : Rl=20355521. C= 01874242 

FI= 00694444 AZ=518. 67: AY=8 80256616 AX=2116 2162 : AW=8 80058256 A V=49 02219586 



/■ ii 

'"DATA INPUT 



""NORMAL FORCE COEFFICIENT - POWER OFF" 



READ D, U0, WF, BT, TT, BD "PHYSICAL PARAMETERS" 

READ H0, R0, V0, G0, T0, AG '"INITIAL CONDITIONS" 

READ TF, HF, DT, PT, TC<1), TC<2), AC '"CONTROL PARAMETERS" 

' " AER0D YNRM I C C0EFF I C I ENTS " 

READ NM*, NA* 

FOR K*=l TO NM* 

READ M<K*): '"MACH NUMBER" 

NEXT K* 

FOR K*=l TO NA* 

READ A<K*): '"ANGLE OF ATTACK" 

NEXT K* 

FOR I*=l TO NM* 

FOR J*=l TO NA* 

READ CA<I*, J*): "AXIAL FORCE COEFFICIENT - POWER OFF" 

NEXT J* 

NEXT IX 

FOR I*=l TO NM* 

FOR J*=l TO NA* 

READ CN<I%JX>: 

NEXT j* 

NEXT IX 

READ 01* 

IF 0I*=6 THEN 528 

READ 00*, A0* 

FOR K*=l TO 00* 

READ M0(K*) 

NEXT K* 

FOR K*=l TO AO* 

READ A0<K*; 

NEXT K* 

FOR I*=l TO 00* 

FOR J*=l TO AO* 

READ C0<I*, J*) 

NEXT J* 

NEXT IX 

FOR I*=l TO 00* 

FOR J*Q=1 TO AO* 

READ N0<IX# JX) 

NEXT J* 

NEXT IX 

CLS 

IF Fl=l THEN 588 

INPUT "DO VOU WANT TO EDIT THE DATA FOR THE FIRST RUN V/N"; E* 

IF E*="Y" THEN 580 

GOTO 600 

IF F1=0 THEN 608 

PRINT "INPUT NEW DATA AND TYPE CONT TO RUN" 

STOP 

D1=DT: FF*=0: PF*=0: SF*=0: TP=PT TP=TT 

CLS 

INPUT "DO YOU WANT A HARD COPY V/N"; At 

IF A*="N" THEN 660 

PRINT "TURN ON LINE PRINTER AND TYPE CONT TO CONTINUE" 

STOP 

ON ERROR GOTO 688 

GOTO 698 

PRINT "TOO MANV CHARACTERS IN TITLE - TRY AGAIN" 

INPUT "TYPE IN RUN TITLE"; T$ 

SR=PI*a.DC2)/4)*FI 

W=W8 

A5=8 

IF TR=0 THEN 760 

BR=CW0-WF)/BT 

"MATRIX INITIALIZATION" 
X<1)=R0 



"AXIAL FORCE COEFFICIENT - POWER ON" 



"NORMAL FORCE COEFFICIENT - POWER ON" 




138 Microcomputing, August 1981 



Listing 1 continued. 






77Q 

789 

790 

806 

810 

820 

830 

840 

850 

860 

870 

880 

890 

900 

916 

928 

930 

940 

959 

960 

970 

986 

990 

1666 

1816 

1826 

1836 

1646 

1658 

1666 

1876 

1688 

1696 

1186 

1110 

1126 
1130 
1140 
1156 
1166 
1176 
1186 
1196 
1266 
1216 
1226 
1238 
1246 
1256 
1268 
1278 
1288 
1296 
1366 
1318 
1328 
1336 
1346 
1356 
1368 
1376 
1386 
1396 
I486 
1418 
1420 
1438 
1440 
1450 
1460 
1479 
1430 



RG=R0 

X<2>=H0+RG 

RL=X<2> 

X<3>=G0*RD 

Gfi*X<3>*57 28 

X<4)=V8 

X<5)=T8 

T=T8 

V=X<4> 

D<1)*V*C0S<:X<3>> 

D<2)=V*SIN(X(3)> 

D<3)=-G*C0S<X<3>W 

D<4>=-G*SIN<X<3)> 

GOTO 2278 



'"XDOT" 
' "ZDOT" 
'"GRMMflDOT" 
"VDOT" 



'"INTEGRfiTION LOOP STARTS HERE" 



FOR IX=1 TO 4 

EUX>-0(IX) 

NEXT IX 

Z=X<2) 

H=R1*Z/<R1+Z> 

T3=82-flV*H 

P=flX/<<fl2/T3>t CC/fW» 

R=RW*P/T3 

fll=RV*SQR(T3> 

Ml=X(4>,'fll 

Ql=8 5*R*-:X(4>[2) 

IF TT=6 THEN 1258 

IF X<5K<T0+BD> THEN TR=0 ELSE TR=TT 

IF X<5>>=<T0+BD+BT> THEN TR=0 

IF XC5><:<T0+BD) THEN 1250 

IF X(5»=<T0+BD> AND FFX=0 THEN 111C 

IF X<5)>=<T0+BD+BT> THEN 1160 

IF FFX=1 THEN 1230 

XD=X<5) 

X<5>»<Tt*M» 

ff;-:=i 

GOTO 1220 

IF FFX=2 THEN 1288 

XD=X<5) 

X-r5) = <T6+BT+BD> 

FFX=2 

DT=X';5>-XD+D1 

GOTO 1286 

DT=X(5)-XD+D1 

w=w0-<:br*x<5>-bd> 

GOTO 1296 

W=W6 

GOTO 1290 

TR=0 

W=WF 

M=W/G 

IF TC(1><X<S><TC<2) THEN A5=AC ELSE A5=0 

IF X<5KTC<1> OR X<5»TC(2) THEN A5=0 

IF AC=0 THEN A5=0 

IF Oi:'.=0 OR TR=0 THEN 1560 

Q*/.=l 

GOTO 1370 

Q'/.=Q'/.+l 

IF A5>=A0<Q*> THEN 1360 

PX*CK-1 

v:y.=i 

GOTO 1420 

IF M1>M0<IOO THEN 1410 

y/.=¥.y.-i 

Sl= < M1-M0 ( JX ) ) / < M0 (. KX > -M0 < JX > ) 
C6=N0 ( JX* ?7. > +S1* < N0 < K'/., ?'/. > -N0 < JXi P'/. > > 
C7"N0<J& OX>+S1*<N0<KX< OX>-Nt<JX« Q!<>> 
C8=C6+ CC7-C6 > * < A5-A0 < PV. > > / < RO ( Q'/. > -R8 < ?V. ) > 
L=Q1*SR*C3 

1498 Cl"OXJ& PX>+Sl*(C8(K/i, PX>-C8<J^ ?'/.>> 
1580 C2=C0< r/., QX>+S1*<C8<K& QX>-Ct<JX< QX> > 
1510 C3=Cl+<:C2-Cl)*<A5-A0(:P?i>>/<A0<QX)-A0<PJi)) 
1520 DR=Q1*SR*C3 

1530 ND=<TR-DR>*C0S<A5*RD)-L*SIN<A5*RD> 
1540 NL= < TR-DR ) *S I N < A5*RD ) +L*COS < A5*RD ) 
1550 GOTO 1796 
1560 Q'/:=l 
1570 GOTO 1590 
1968 QX«OX+l 

1590 IF R5>-ft<QX) THEN 15S0 
1600 PX-QX-1 
1610 KX-1 
1620 GOTO 1646 

1630 k:/.'=k;:*i 

1640 IF NDfKKX) THEN 1630 

1650 JX=KX-i 

1660 5i*<m.-ff< JX) >/<H<KX>-H<JX» 

1670 C6=CN <y/„ P'/.>+Sl*<CN(K.X, PX)-CN<J& PX) > 

1688 C7-CK<JX, aX)+Sl*<CN<K& Q'/. >-CN< y/„ Q'/.> ) 

1696 C8=C6+<:C7-C6>*<:A5-A<:P;0V<A<QX>-A<P/0> 

1768 L=Q1*SR*C8 

1718 Cl=CA(j;^ P*)+S1*<CFKKK, PX>-CR<J& P m /.» 

1728 C2=CA < JX, QX > +S1* < CA < ¥?., QX ) -CA < J'/., 0'/. > > 

1738 C3=Cl+<C2-Cl>*':A5-A<PX))/<A<QX)-A<:P , /.)> 

1748 DR=Q1*SR*C3 

1756 IF TT=6 THEN ND=-DR*C0S<A5*RD>-L*SIN<A5*RD) 

1768 IF TT=8 THEN 1788 

1778 ND=<TR-DR>*C0S<A5*RD)-L*SIN<A5-RD> 

1786 NL=aR-DR)*SIN<A5*R0)+L*C0S(:A5*RD) 

1798 D' 4>=-G*SIN<X<3>)+ND/M 

1806 D<3)=-G*C0S<X<3)>/V+NL/<M*V> 

1816 LG=X<3) 



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DI09 Digital Interface 

Monitor or control 32 circuits in any 

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Measure time intervals or count pulses 
Plug into BCD, parallel, or switch closure 

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UI16 Isolated Power Interface 

Control 110V AC circuits from a program 
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Start with one circuit — expand to dozens 




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^See List of Advertisers on page 194 



Microcomputing, August 1981 139 



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Listing 1 continued. 

1820 LV=X<4) 
LR=X<1) 
LA=X<2) 
LT=X<5> 

X<3)=X<3)+0. 5*DT*<D<3)+E<3)) 
X<4)=X<4)+0. 5*DT*<D<4)+E<4)) 
D(1)=X(4)*C0S<X<3)) 
D<2)=X<4)*SIN<X<3)) 
X<i)=X<i)+0 5*DT*<D<1)+E<1)) 
X<2)=X<2)+0 5*DT*<D<2)+E<2)) 
IF X<5)=<T0+BD) THEN 1950 
IF X<5)=<T0+8D+BT) THEN 2030 
GOTO 2110 
IF TT=0 THEN 2110 
IF A*="N" THEN 1990 

LPRINT X<5); TAB<15XX<1V3280. ); TAB<31)Xk2); TAB<47XX<3)*57. 28); TAB<63)X<4); 
GOTO 2000 

PRINT USING F$; X<5), <X<1V2280. ), X<2), <X<3)*57. 28), X<4) 
DT=D1-DT 

IF DT=0 THEN DT=D1 
GOTO 2120 
IF TT=0 THEN 2110 
IF flt="N" THEN 2070 

LPRINT X<5);TAB<15XX<l)/3280 ); TAB<31)X<2); TAB<47XX<3)*57. 28); TAB<63)X<4); 
GOTO 2088 

PRINT USING F$; X<5), <X<l)/3280 >, X<2), <X<3)*57. 28), X<4) 
DT=D1-DT 

IF DT=8 THEN DT=D1 
GOTO 2120 
DT=D1 

IF X<5)>=TF THEN 2220 
IF XC2XCHF+RG) AND X<3)<0 THEN 2550 
IF X<5)>=TP THEN 2210 
X<5)=X<5)+DT 
V=X<4) 
GOTO 940 

'"INTEGRATION LOOP ENDS HERE" 
'"OUTPUT LOGIC FOLLOWS" 



1830 
1848 
1850 
1860 
1870 
1880 
1890 

1900 

1910 
1920 
1930 
1940 
1950 
1960 
1970 
1980 
1990 

2000 

2010 
2020 
2030 
2048 
2050 
2060 
2070 
2080 
2090 

2100 

2110 

2120 

2130 

2140 

2150 

2160 

2170 

2180 

2190 

2200 

2210 

2220 

2230 

2240 

2250 

2260 

2270 

2280 

2290 

2300 

2310 

2320 

2330 

2340 

2350 

2360 

2370 

2380 

2390 

2400 

2410 

2428 

2430 

2440 

2450 

2460 

2470 

2480 

2490 

2508 

2510 

2520 

2530 

2540 

2550 

2560 

2578 

2575 

2580 

2590 

2600 

2610 

2620 

2630 

2640 

2650 

2660 

2678 

2680 

2690 

2700 

2710 

2720 

2730 

2740 

2750 

2760 

2770 

2780 

2790 

2880 

2810 

2820 

2830 

2840 



IGNITION" 



BURNOUT ' 



TAB<5)"TIME"; TAB< 13) "RANGE"; TAB < 28) "ALTITUDE"; TAB< 3D" GAMMA"; TAB< 38)" VELOCITY" 
TAB(4)"CSEC)";TAB<14)"<KM)";TAB<22)"<FT)";TAB<31)"(DEG) M ;TAB<38)"<FT/'SEC)" 



TA6<5)T$ 

" "CHR$<10) 

" "CHRt<10) 

TAB<2)"TIME"; TAB< 16) "RANGE"; TAB < 31) "ALTITUDE"; TAB<47) "FLIGHT PATH"; T AB < 63 >" VELOCITY 

T AB < 32 ) " < AGL ) " ; TAB < 50 ) " ANGLE " 

TAB<2)"<SEC)";TAB(16)"<KM)";TAB<33)"<FT)";TAB<50)"<DEG)";TAB<63)"<FT/SEC)" 

" "CHR*<10) 



TP=TP+PT 

T=X<5) 

RG=X<l)/3280. 

AL=X<2) 

GA=X<3)*57. 28 

V=X<4) 

IF A*="Y" THEN 2418 

IF SFX=1 THEN 2350 

CLS 

PRINT T$ 

PRINT 

PRINT 

PRINT 

SFX=1 

IF T>=TF THEN 2710 

IF AL<<HF+AG) AND GA<0 THEN 2550 

F$=" ######. ##" 

AP=AL-AG 

PRINT USING F$; T, RG, AP, GA, V 

GOTO 2150 

IF T>=TF THEN 2710 

IF AL«HF+AG) AND GA<0 THEN 2550 

IF PF^=1 THEN 2520 

PFX=1 

LPRINT 

LPRINT 

LPRINT 

LPRINT 

LPRINT 

LPRINT 

LPRINT " 

AP=AL-AG 

LPRINT T; TAB<15)RG; TAB<31)AP; TAB(47)GA; TAB<63)V 

GOTO 2150 

AL=HF+AG 

X(2)=ABS<X(2)) 

DI=(LA-(HF+AG))/(LA-X<2)) 

T=X(5)-DT-KDT*DI) 

RG=<LR+(<X(l)-LR)*DI))/3280 

GA=<LG-K<X<:3>-LG>*DI))*57. 28 

V=LV+<<X<4)-LV)*DI) 

AP=AL-AG 

IF A$="Y" THEN 2678 

PRINT USING F$; T, RG, AP, GA, V 

PRINT 

PRINT "FLIGHT TERMINATED AT CUTOFF ALTITUDE" 

GOTO 2790 

LPRINT T; TABC15)RG; TABC3DAP; TAB<47)GR; TflB<63)V 

LPRINT " "CHR*<10) 

LPRINT TAB < 15) "FLIGHT TERMINATED AT CUTOFF ALTITUDE" 

GOTO 2290 

IF A*="Y" THEN 2760 

PRINT USING F$; T, RG, AP, GA, V 

PRINT 

PRINT "FLIGHT TERMINATED ON MAXIMUM TIME" 

GOTO 2790 

LPRINT T; TAB(15)RG; TAB<31)AP; TAB(47)GA; TAB<63)V 

LPRINT " "CHR$<:i0) 

LPRINT TAB< 15) "FLIGHT TERMINATED ON MAXIMUM TIME" 

Fl=l 

RESTORE 

T$=" " 

INPUT "DO YOU WANT TO MAKE ANOTHER RUN"; R$ 

IF R*="Y" THEN 580 

END 



140 Microcomputing, August 1981 





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Microcomputing, August 1981 141 



Plunging deep into the heart of the steaming ROM jungle. 



An Atari Disassembler 



By William L. Colsher 



When a new computer is intro- 
duced, we hobbyists are natu- 
rally curious about how it operates. 
How does it use RAM? Are undocu- 
mented features buried in the ROMs? 
What tape recording format does it 
use? To answer these questions re- 
quires patience and experience; dig- 
ging through the ROMs and the re- 
served work areas requires a tool. 
That tool is the disassembler. 

A disassembler is the opposite of an 
assembler. Instead of generating ma- 
chine code as output, it accepts ma- 



chine code and produces assembly- 
language listings as output. Natural- 
ly, the original labels aren't repro- 
duced, but the result is a lot easier to 
use than a hex dump. 

Because a disassembler is the oppo- 
site of an assembler, you would natu- 
rally expect that the two programs 
would be similar in structure. You 
would hope to see tables of machine 
operation codes (op codes), mnemon- 
ics, addressing modes and instruction 
lengths. The tables are used in much 
the same way as an assembler would 



Program listing. 



100 
110 

120 

130 

140 

150 

160 

170 

180 

190 

Z0O 

210 

220 

230 

240 

250 

260 

270 

280 

290 

1000 

1010 

1020 

1030 

1040 

1050 

1060 

1070 

1080 

1090 

2000 



DIM RS( 168),B«(3),0O 151 ),Cn> 151) , F«( 4 ) , H*( 4 ) , D%< 1 ),T*f4),LNt 13) 
FOR 1-1 TO 56 
RERD B» 

R»(( 1-1 )*3+l )=B» 
NEXT I 

FOR 1-1 TO 151 
READ R,B 
0C( I )-R:CD( 1 )«B 
NEXT I 

FOR 1-1 TO 13--RERD R: LN( I )-R: NEXT I 
GRRPHICS 

PRINT "Enter all input in hwx idac ima I " 
Di s -asseirib I c from:"; 



PRINT 

INPUT F* 

PRINT * to:"; 

INPUT T» 

HS-FS : GOSUB 10000: F-INT< H )+l : IF H« 

HS-T«: GOSUB 10000: T-INTC H )+l : IF H 

GRRPHICS 

POSITION 2,23 

REM *»*STRRT DIS-RSSEMBLY LOOP 

B-PEEK(F) 

GOSUB 10100 

IF I SOP THEN GOSUB 2000 

IF NOT ( I SOP ) THEN GOSUB 3000 

IF F<«T THEN GOTO 1010 

PRINT "DIS-RSSEMBLY COMPLETE" 

PRINT "PRESS RETURN TO CONTINUE" 

INPUT H» 

GOTO 200 

REM ••♦DISPLRY RN INSTRUCTION 



■0 
=0 



THEN 
THEN 



F" 
T« 




'0 




use them but in the opposite direc- 
tion. For example, a disassembler 
takes the op code and generates a 
mnemonic, while an assembler ac- 
cepts a mnemonic and generates an 
op code. 

If you now look at the program list- 
ing, you'll see that all these tables are, 
in fact, defined in line 100. A$(168) is 
a string containing the mnemonics. 
OC(151) is an array that holds the op 
codes. CD(151) combines with LN( 13) 
to provide the information on ad- 
dressing modes and instruction 
lengths. CD(151) also holds a pointer 
for each op code into the A$ string to 
enable the computer to find the cor- 
rect mnemonic. The DATA state- 
ments in lines 30000 through 30310 
are read to fill these tables. 

To save space this program com- 
bines the pointer to the mnemonic ta- 
ble with the addressing mode. Table 
CD contains four-digit numbers: the 
first two digits are the mnemonic 
number and the second two are the 
addressing mode. The addressing 
mode points into the array LN, which 
contains the lengths of the instruc- 
tions using the various addressing 
modes. 

How It Works 

Now let's take a look at how the 
disassembler works. In the listing, 

Address correspondence to William L. Colsher, 
1711 Robin Lane, Lisle, IL 60532. 



142 Microcomputing, August 1981 



lines 100 through 290 perform all the 
necessary setup functions: filling the 
tables from the DATA statements 
and getting the start and end ad- 
dresses from the user. 

Lines 1000 through 1090 form the 
main loop of the program. After get- 
ting a byte to be disassembled, the 
subroutine at line 10100 is called. If 
the byte is an operation code, the sub- 
routine beginning at line 2000 is 
called to display it. If the byte is not 
an op code, the subroutine at line 
3000 is called. Both of these routines 
increment the pointer into memory F 
as appropriate. The loop continues 
until F is greater than or equal to T 
(the highest location to be disassem- 
bled). 

Line 2000 begins the section of 
code that actually performs the disas- 
sembly. First, the routine beginning 
at line 10200 is called to output the 
address (the value in F). Then, sever- 
al routines starting at line 9000 take 
over to display the hexadecimal ma- 
chine code, the mnemonic and oper- 
ands, and the ASCII version of the op 
code. 

The ASCII version of the op code is 



Listing continued. 



2010 

2020 

2025 

2030 

3000 

3010 

3020 

3030 

3040 

3050 

9000 

9010 

9020 

9030 

9040 

9050 

9060 

9070 

9085 

9090 

3100 

9110 

9120 

9130 

9140 

9150 

9160 

9200 

9210 
9250 
9260 
9300 
9310 
9320 
9330 
9350 
9360 
9400 
9410 
9450 
9460 
3500 
9510 
9550 



TO 3: PRINT 
MNEMONIC 



NEXT I: PRINT 



GOSUB 10200 

GOSUB 9000 

PRINT 

RETURN 

REM »**PRINT fi DfiTfl BYTE 

GOSUB 10200 

B=PEEK(F):GOSUB 10400 

POSITION 16, 23: PRINT "DftTft'; 

POSITION 30,23:PRINT "' * ; CHR»( PEEKCF ) ); 

F=F+1: RETURN 

REM ♦♦♦PRINT HEX OPERRTION 

MN-INTC CD( OP1 )/100 ) 

flM=INT(CD(OPl )-100«MN)+l 

FOR 1=0 TO LN(RM)-1 

B=PEEK(F+I) 

GOSUB 10400 

NEXT I 

FOR I-LN(ftM) 

REM ♦♦♦PRINT 

BS=ft*( (MN-1 )*3+l ) 

PRINT B»; " ' ; 

ON ftM-1 GOSUB 9200,9650,9250,9300,9350,9400,9450,9500,9200,9200,9550,9600 
POSITION 30,23:PRINT "'"; 
FOR 1=0 TO LNCftM 1-1 
PRINT CHR»(PEEK(F+I ) ); 
NEXT I: PRINT "' '; 

F=F+LN( AM ) : RETURN 

REM ♦♦♦IMMEDIATE. ACCUMULATOR & RELATIVE 

B=PEEKA F ■■ + 1 ) : GOSUB 10400: RETURN 

REM ♦♦♦ZERot AGE X 

GOSUB 9650: PRINT ' 

REM ♦♦♦ABSOLUTE 

B=PEEK( F+2 ) : GOSUB 

B-PEEKC F+ 1 > : GOSUB 

RETURN 

REM ♦♦♦ABSOLUTE X 

GOSUB 9300: PRINT 

REM ♦♦♦ABSOLUTE Y 

GOSUB 9300: PRINT ' 

REM ♦♦♦INDIRECT X 

PRINT M";: GOSUB 9200: PRINT 

REM ♦♦♦INDIRECT Y 

PRINT •<";: GOSUB 9200: PRINT 

REM ♦♦♦INDIR 



.X"; '.RETURN 

10400 
10400 



: RETURN 



RETURN 



),Y" 



RETURN 



RETURN 




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Microcomputing, August 1981 143 



Listing continued. 



9560 PRINT " ( " ; : GOSUB 9300: PRINT " ) " ; : RETURN 

9600 REM ***ZERO PAGE Y 

9610 GOSUB 9650:PRINT ",Y';:RETURN 

9650 REM **«ZERO PAGE 

9660 PRINT ■(";:GOSUB 9200:PRINT ")";:RETURN 

10000 REM «**HEX TO DECIMAL 

10010 H-0:D-0:T-0 

10020 FOR I-LEN(H«) TO 1 STEP -1 

10030 DS=HS( I ) 

10040 T-ftSC(DS)-48 

10050 IF T>9 THEN T-T-7 

10060 H=H+T*( 16tD ) 

10070 D=D+1 

10080 NEXT I 

10090 RETURN 

10100 REM ••♦SEE IF B IS VALID OP CODE 

10110 ISOP=0 

10120 FOR OPl=l TO 151 

10130 IF B-OC(OPl) THEN GOTO 10160 

18140 NEXT OP1 

10150 RETURN 

10160 POP : I SOP- 1 : RETURN 

10200 REM ••♦HEX ADDR. FROM F 

10205 P-l:Tl-F 

10210 FOR D-3 TO STEP -1 

10220 FOR E-l TO 16 

10230 IF F-(E»( INT(( 16TD)+1 ) ) )<0 THEN GOTO 10250 

10240 NEXT E 

10250 POP :E-E-l:F-F-(E*(INT( 16tD) + D) 

10260 E«E+48:IF E>57 THEN E-E+7 

10270 HS(P)-CHRSCE) 

10280 P-P-H 

10290 NEXT D 

10300 F=T1 

10310 PRINT H«;" ";:RETURN 

10400 REM •♦•CONVERT & PRINT 1 BYTE 

10405 BS="":P-1 

10410 FOR D=l TO STEP -1 

10420 FOR E-l TO 16 

10430 IF B-(E*( INT(( 16TD) + 1 ) ) )<0 THEN GOTO 10450 

10440 NEXT E 

10450 POP :E-E-1:B«B-(E»( INTC 16TD) + 1 )) 

10460 E-E+48HF E >57 THEN E-E+7 

10470 B»(P )=CHR«(E) 




displayed because it is quite possible 
that a piece of data could be inter- 
preted as a legal instruction. For ex- 
ample, the ASCII code for the charac- 
ter X is the same as the op code for 
the instruction CLD (a hex D8). In 
some cases, of course, there will be 
data that is not printable ASCII, but at 
least with this technique we can 
catch some of it. 

Line 3000 begins the routine to 
handle data that the program is able 
to recognize as data (since it has dis- 
covered that the byte is not a legal op 
code). Once again the address is dis- 
played, as well as the byte at that lo- 
cation. Then, the word DATA is 
printed and the ASCII version of that 
byte is displayed in the appropriate 
column. 

Occasionally, the ASCII version of 
a byte turns out to be a control code. 
The result of printing such codes on 
the screen can sometimes be interest- 
ing. I have left out any code to detect 
such codes but, if the occasional 
skipped line or tab is offensive, it 
would be a simple matter to detect 
and override (perhaps with blanks) 
their printing. 



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144 Microcomputing, August 1981 



Now you're ready to go snooping 
through your Atari's ROMs. If you're 
not familiar with the 6502, here are a 
couple of addresses that may interest 
you (or provide a place to start snoop- 
ing). Locations FFFC-FFFD (in hex, 
of course) contain the address to 
which a 6502 branches when a reset 
occurs. Locations FFFA-FFFB con- 
tain the address that is branched to as 
a result of a non-maskable interrupt. 
Locations FFFE-FFFF contain the ad- 
dress that is branched to as a result of 
a maskable interrupt. With these as a 
starting point, you should be able to 
discover quite a lot about how your 
Atari computer works. 

For the sake of standardization, I 
have used the mnemonics and nota- 
tion in 6502 Software Gourmet Guide 
and Cookbook, except that to make 
zero page addressing more distinct 
from immediate mode, I have placed 
parentheses around zero page oper- 
ands. Since I'm new to the 6502 and 
don't yet have the Atari Assembler 
cartridge, it is possible that the con- 
ventions I have chosen are not stan- 
dard. If anyone is offended by my 
choice, please accept my apologies. ■ 



Listing continued. 

10480 P-P+l 

10490 NEXT D: PRINT B«; : RETURN 

30000 REM ***MNEMONICS 

30005 DftTfi RDC,ftND f flSL,BCC,BCS,BEQ,BIT,BMI,BNE f BPL 

30010 DATA BRK,BUC,BUS,CLC,CLD,CLI,CLU f CMP,CPX,CPY 

30020 DftTft DEC.DEX.DEY.EOR, INC, INX, INY, JMP, JSR.LDO 

30030 DftTfl LDX,LDY,LSR,NOP,ORR,PHft,PHP,PLfi,PLP,ROL 

30040 DRTR ROR t RTI,RTS,SBC,SEC,SED,SEI t STR f STX f STY 

30050 DftTR TRX,TRY,TSX,TXR,TXS,TYR 

30100 REM *»*OP CODES, RDBRESSING MODES 

30110 DRTR 105,101,101,102,117,103,109,104,125,105,121,106,97,107,113,108,41,201 
, 37 , 202 

30120 DRTR 53,202,45,204,61,205,57,206,33,207,49,208,10,309,6,332,22,303,14,304, 
40,305 

30130 DRTR 144,410,176,510,240,610,36,702,44,704,48,810,208,910,16,1010,0,1100,8 
0,1210 

30140 DRTR 112, 1310, 24 , 1400, 216, 1500,88, 1600, 134, 1700,201 , 1801 , 197, 1802,213, 1803 
,205, 1804,221, 1805 

30150 DRTR 217,1806,193,1307,209,1808,224,1901,228,1902,236,1904,192,2001,196,20 
02 , 204 , 2004 

30160 DRTR 198,2102,214,2103,206,2104,222,2105,202,2200,136,2300,73,2401,69,2402 
,85,2403 

30170 DRTR 77,2404,93,2405,89,2406,66,2407,81,2408,230,2502,246,2503,238,2504,25 
4,2505 

30180 DRTR 232 , 2600, 200 , 2700 , 76 , 2804 , 108, 281 1 , 32 , 2904 , 169, 3001 , 165, 3002, 181 , 3003 
, 173 , 3004 , 1 89 , 3005 

30190 DRTR 185,3006,161,3007,177,3008,162,3101,166,3102,172,3112,174,3104,190,31 

06 

30200 DRTR 160, 3201 , 164, 3202, 180, 3203, 172, 3204, 138, 3205, 74, 3309, 70, 3302, 86, 3303, 
78,3304 

30210 DRTR 94,3305,234,3400,9,3501,5,3502,21,3503,13,3504,29,3505,25,3506,1,3507 
,17,3508 

30220 DRTR 72 , 3600 , 8 , 3700 , 104 , 3800 , 40 , 3900 , 42 , 4009 , 38 , 4002 , 54 , 4003 , 46 , 4004 , 62 , 40 
05,106,4109 * 

30230 DRTR 102,4102,118,4183, 110,4104,126,4105,64,4200,96,4300,233,4401,229,4402 
, 245 , 4403 , 237 , 4404 

30240 DRTR 253, 4405, 249, 4406, 225, 4407 ,<Z41 , 4408,56, 4500, 248, 4600, 120, 4700, 133, 480 

2,149,4803, 141,4804 

30250 DRTR 157,4805, 153,4806, 129, 4807 , 145, 4808, 134,4902, 150,4912, 142,4904, 132,50 

02,148,5003, 140,5004 

30260 DRTR 170,5100, 168,5200, 186,5300, 138,5400, 154,5500, 152,5600 

30300 REM ***RDDRESSING MODE LENGTHS 

30310 DRTR 1,2,2,2,3,3,3,2,2,1,2,3,2 



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Apple H.S. Serial Card $195 $159. 

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Apple Fortran $200 $169. 

Apple Pilot $150 $125. 

Apple Writer $75 $60. 

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Microcomputing, August 1981 145 



With the Cognivox speech input/output peripheral, your computer can understand what you say and 

answer you back. 



The Sorcerer Speaks 



By Peter Vernon 



The Cognivox VIO-132 from Voice- 
tek, Inc. (PO Box 388, Goleta, CA 
93116), is a speech recognition and 
voice-response peripheral for the Ex- 
idy Sorcerer. [Editor's Note: Voicetek 
also manufactures models for 
AIM-65, Apple II, Commodore PET 
and CBM, and the TRS-80 comput- 
ers.] Up to 32 words or short phrases 
can be entered into the computer's 
memory and recalled as desired. Any 
of the stored words can be recognized 
by the computer and used to control 
the flow of a program. Music and 
sound effects can also be reproduced. 
The length of Cognivox' s voice-re- 
sponse vocabulary depends on the 
length of the words used and the 
memory size of your Sorcerer. At 
least 32K of RAM is required for max- 
imum capability, but the Cognivox 
can be used with 16K; in this case the 
response vocabulary will be limited 
to 12-16 short words, but the word 
recognition vocabulary will still be 32 
words. 

From the outside the Cognivox is 
deceptively simple. It is enclosed in a 
plastic box measuring 159 mmx96 
mmx50 mm, with a 7 cm speaker 
covered by a mesh grille, a volume 
control and a socket for a microphone 
at one end of the box. A dynamic mi- 
crophone is supplied with the periph- 
eral, along with a cassette of operat- 
ing and demonstration programs. An 
18-page user's manual is also pro- 
vided, containing a brief description 
of the operation of the device and fur- 



ther sample programs. 

The unit comes fully assembled, 
ready to plug into the parallel I/O 
port of the Sorcerer and run immedi- 
ately. 

Before discussing the operation of 
the Cognivox in more detail, how- 
ever, let's take a look at the various 
methods of speech synthesis avail- 
able for use with small computers. 

Speech Synthesis 

Three methods can be used to pro- 
duce speech from a computer. Speak- 
ing devices such as those from Texas 
Instruments use a phoneme synthesis 
method. Their speech synthesizer 
chip, used in the Speak & Spell and as 
a peripheral for the TI 99/4 home 
computer, is an array of program- 
mable filters, and noise and tone 
sources. Any desired sound can be re- 
produced by manipulating the pa- 
rameters of the filters. This method is 
also used by the Computalker and the 
Votrax Type 'n Talk speech synthe- 
sizers, although they use discrete 
components to carry out the same op- 
erations as the TI chip. 

The main difference between the 
operation of the TI synthesizer and, 
for example, the Votrax is that the TI 
devices contain code for complete 
words stored in ROM, while the Vo- 
trax synthesizer stores codes for the 
individual phonemes of the English 
language, allowing words to be built 
up from combinations of sounds. The 
Votrax synthesizers are thus more 



flexible, although much program- 
ming effort is needed to use them ef- 
fectively. 

The Computalker is similar to the 
Votrax devices, although it also pro- 
vides direct control of nine of the 
speech parameters in addition to 
phoneme-based synthesis. 

The second method of reproducing 
speech is digital storage of speech in- 
formation, using a compression algo- 
rithm which eliminates the redun- 
dancy of speech information to con- 
serve memory. Data is read out and 
then expanded to drive a digital-to- 
analog converter and an amplifier. 
This is the method used in Digitalker 
DTI 050, the National Semiconductor 
speech synthesis set. (See 'Build a 
Low Cost Speech-Synthesizer Inter- 
face" by Steve Ciarcia in the June, 
1981 Byte for a board based on this set 
that can be used with a number of 
computers.) 

The SD200 Supertalker from 
Mountain Computer also uses a data 
compression technique. This is the 
only device besides the Cognivox 
which offers both speech input and 
output in one peripheral. 

The third possible technique is dig- 
ital recording, the method used by 
the Cognivox. Speech signals from a 
microphone are filtered, and the out- 



Peter Vernon, 31 Georgina St., Newtown, NSW 
2042, Australia, is a free-lance technical writer 
and computer systems consultant. 



146 Microcomputing, August 1981 



put of the filters is sampled period- 
ically and stored in the computer's 
memory. Playback is a matter of 
reading out the digital information 
and converting it to analog form to 
drive an amplifier and speaker. Word 
recognition is performed by compar- 
ing the patterns of the input word 
with the patterns in memory and re- 
porting the closest match. 

The advantage of phoneme-driven 
synthesizers is that, in theory, any 
word can be reproduced. In practice, 
however, the intelligibility and qual- 
ity of the speech suffers unless the 
synthesizer is carefully programmed 
by an experienced user. Fixed vocab- 
ulary synthesizers store the data for 
each word in ROM, eliminating the 
need to program each sound segment 
of the word individually, but, of 
course, the vocabulary is limited to 
the words already coded in the ROM. 
In some applications this is not a 
disadvantage, as only a fixed vocab- 
ulary is necessary. Telesensory Sys- 
tems, Inc., has marketed a talking 
calculator using this approach, and 
has had considerable success. Both 
Telesensory Systems and Texas In- 
struments offer fixed vocabulary syn- 
thesizer modules for OEM applica- 
tions. 

Digital recording is the easiest sys- 
tem to use, and has the advantage 
that the vocabulary can be easily 
changed. The disadvantage is that the 
technique uses large amounts of 
memory to store the speech data. The 
Cognivox uses a digital sampling 
technique that sacrifices speech qual- 
ity for memory storage and ease of 
use. The sampling rate of about 6 kHz 
limits the bandwidth of speech to 
about 3 kHz, creating a degree of dis- 
tortion similar to speech heard over a 
telephone. Intelligibility can be quite 
good if care is taken in entering the 
words into memory when the vocab- 
ulary is first created. 

A second advantage of digital re- 
cording is that the stored data can be 
used to identify a word which has 
previously been entered into mem- 
ory. The success rate of the recog- 
nizer is said to be 98 percent, but in 
practice seems to be closer to 85 per- 
cent. This success rate is dependent 
on the speaker. You must pronounce 
each word in the same way each time 
it is used, and the device will only 
recognize the voice of the person who 
trained it. 

Using the Cognivox 

The Cognivox plugs into the paral- 



lel port of the Sorcerer, and takes its 
power from the computer. The Moni- 
tor stack and the BASIC stack must 
be relocated downwards to create a 
protected area of memory in which 
the Cognivox machine-language driv- 
er and speech data can be stored. A 
BASIC program called BOOT is pro- 
vided on the accompanying cassette 
to perform this relocation. 

The software supplied on the dem- 
onstration cassette is recorded at 300 
baud for improved reliability. This 
naturally increases the time taken to 
load the program, but is not a serious 
disadvantage. The manual accompa- 
nying the Cognivox suggests that you 
might like to record the programs at 
1200 baud to speed loading. (The Sor- 
cerer provides for both baud rates.) 

After BOOT has been loaded and 
run, approximately 4K of RAM re- 
mains for application programs. The 
machine-language driver, VOX2, is 
not position-independent, and must 
be loaded into RAM at addresses 
1200H to 15FFH. Data tables for this 
program occupy addresses 1600H to 
1CFFH, and speech data is stored 
from 1D00H to the end of RAM 
(3FFFH for a 16K Sorcerer, 7FFFH 
for a 32K machine). [Editor's Note: 
Voicetek has informed us that a relo- 
cated version of VOX2 is available 
starting at 7200H for users with 48K 
Sorcerers. This version allows more 
space for user programs and does not 
conflict with DOS systems.] 

All the application programs sup- 
plied with the Cognivox will run on a 
16K Sorcerer, although a 32K Sorcer- 



er provides more room for the storage 
of speech data, so that the voice- 
response vocabulary can be slightly 
longer and use longer words. 

After running BOOT and loading 
the machine-language driver, your 
applications programs can be loaded. 
A demonstration program called 
PROG2 is provided, and is a good ex- 
ample of the abilities of the system. 
The program provides six options, 
covering entry of a vocabulary, play- 
back and recognition. Training the 
Cognivox requires three passes 
through the vocabulary. On the first 
pass the device samples the charac- 
teristics of your voice in preparation 
for the the second pass, which enters 
the spoken words into memory. The 
third pass plays back the stored 
words and asks you to repeat each 
one into the microphone to fine-tune 
the system. 

The words entered can be played 
back using option 2 of the demonstra- 
tion program. I had fun getting my 
computer to say "Hello, I am a com- 
puter. How can I help you?" Each 
word of a sentence is entered sep- 
arately, so it requires some practice 
to achieve a natural-sounding intona- 
tion. 

Options 4 and 5 exercise the voice 
recognition abilities of the unit. Op- 
tion 4 provides recognition with 
voice response; you say the word, 
and the computer searches the stored 
data for a matching pattern and 
speaks the word it has found. Option 
5 is similar, except that rather than 
speaking the word the computer dis- 




Voicetek 's speech synthesis unit for the Sorcerer. 



Microcomputing, August 1981 147 



plays the number of the word it has 
found. (Words are numbered in the 
data area in the order in which they 
were entered into memory.) Using 
this program as a guide, it is easy to 
write BASIC programs which recog- 
nize a word and then perform some 
action on the basis of the word rec- 
ognized. This is the operating prin- 
ciple of the two demonstration game 
programs supplied on the cassette. 

Since the Cognivox uses a digital 
recording technique, most of the 
characteristics of the speaker' s voice 
are retained and reproduced; the unit 
faithfully reproduces tones of voice, 
inflections and accents. 

Cognivox is useful for more than 
just games, as another program on 
the supplied cassette demonstrates. 
VDUMP is a verbal memory dump. 
After entering the numbers from zero 
to nine and the letters from A to F, via 
the microphone, you can specify an 
area of memory which will be ex- 
amined. The program displays ad- 
dresses and data on the screen for the 
selected area of RAM, and at the 
same time the Cognivox speaks the 
hex value of the byte stored in each 
memory location. It is also possible to 



use the routines from PROG2 to re- 
verse the process and have the Cogni- 
vox enter data into RAM in response 
to a spoken message. Entering a ma- 
chine-language program is then a 
matter of speaking into the micro- 
phone. 

Not Just Words 

The Cognivox is not restricted to re- 
producing words. A demonstration 
program is supplied which illustrates 
its music and sound-effects capabil- 
ities, first with random computer 
music and then with classical and 
popular tunes. Several examples of 
similar programs are given in the op- 
erating manual, together with a list of 
values to produce specific notes of 
the musical scale. You can control 
both the frequency and the duration 
of the sounds. 

It is at this point that a limitation of 
the Cognivox, and of the manual, be- 
comes apparent. To produce middle 
C the manual suggests that you poke 
a value of 268 to a location in mem- 
ory. It is simply not possible to store 
any number higher than 255 in a sin- 
gle eight-bit byte, and, if an attempt is 
made to do so on the Sorcerer, a 



Function Call (FC) error message will 
be displayed. This means that the 
lowest note possible for the Cognivox 
is C sharp above middle C. There 
may be some way around this prob- 
lem, but the manual makes no men- 
tion of it, and it seems that the author 
of the manual was unaware that any 
problem existed. 

This is the one fault I found in the 
system, and is an exception to the 
generally fine presentation and clar- 
ity of the manual. 

Other programs supplied on the 
demonstration cassette are VOTH, a 
voice-operated version of the game 
Othello, and VTRAP, a game in which 
you and the computer maneuver a 
trace on the display screen to corner 
the opponent and block any further 
movement. VOTH uses the word rec- 
ognition ability of the Cognivox to let 
the player enter his or her moves 
verbally, while to play VTRAP you 
first enter the words "left,'' "right," 
"down," "go up" and "faster" and 
train the Cognivox to recognize 
them— the player's moving trace on 
the display then responds to these 
commands. 

The final program supplied is 



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148 Microcomputing, August 1981 




The guy on the left 

doesn't stand a chance 




The guy on the left has two file folders, a news maga- 
zine, and a sandwich. 

The guy on the right has the OSBORNE 1 ® , a fully 
functional computer system in a portable package the size 
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1600 typed pages, stored on floppy diskettes. 

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called CALC, and turns the Sorcerer 
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arithmetic operation requested. The 
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Although this demonstration pro- 
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infinitely, to turn your Sorcerer into a 
talking, programmable scientific cal- 
culator with RAM. 

The user's manual gives further ex- 
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playing back speech, and for creating 
music and sound effects. It also pro- 
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the Cognivox to an external ampli- 
fier. The quality of the voice output 
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tirely covered with a thick blob of 
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150 Microcomputing, August 1981 



In any environment where inquisitive and sometimes destructive minds run rampant, protection is a must. 



Student'Proof 
Your Computer 



By Ken Reid 



A hobbyist's computer is in a pro- 
tected environment. The user 
has money invested in his system, 
and takes precautions to avoid such 
expensive mistakes as spilling Pepsi 
on his keyboard. 

But schools are different. If a frag- 
ile input device is left unsupervised, 
it won't be functioning for long. Soft- 
ware, too, is vulnerable; it takes only 
one clever or malicious student who 
knows how your system works to 
produce startling changes in your 
carefully constructed educational 
program. 



♦5V 
4 



ICVF 



LM 
309K 



T 

X 



-BOX 
-8V 

■GND 




ACK 



J 



HALL EFFECT 
KEY SWITCH 
(7 USED) 

MICROSWITCH 
PK 8913-3 



300 



20d 



^'^^ 




Fig. 1. Keybox circuit. 




The input keybox. 

Experiences of this type were up- 
permost in our minds when we de- 
veloped a classroom-sized (24 work 
stations) input system for a micropro- 
cessor-controlled CAI system for our 
Health Sciences Library at the Uni- 
versity of Louisville. Our student ac- 
cess terminals had to be foolproof. So 
we developed an input keybox. 

Why use special input keyboards? 
First, the signals enter your program 
and cannot be used for anything else. 
This restriction is an absolute neces- 
sity for any system which is intended 
for, or exposed to, unrestricted public 
access. The operator's console is 
separate and can be kept safely 
behind locked doors. 

Second, the user is less likely to be 
confused if his options are restricted. 
Few CAI programs require more 
than four or five options at each 
choice point. 

Third, simple keyboards cost less 
than complex ones, both in dollars 
and maintenance. 

The box is made of heavy black 
plastic. The key assembly and cir- 
cuitry is mounted on the cover for 



easy construction, and the cover is at- 
tached to the box by four nylon ma- 
chine screws. These are sealed after 
assembly with plastic cement. The 
seven keys are Hall-effect switches 
(Microswitch PK 8913-3), which we 
obtained as a surplus lot from NCE 
Compumart. We used blank keycaps 
and inserted our special labels. 

The keybox circuit is shown in Fig. 
1. Each box provides a one-bit "I'm 
here' ' signal as long as it is connected 
and another three bits indicating 
which key has been pressed. Once a 
key has been pressed the output 
locks; further keypresses have no ef- 
fect until the computer reads the 
signal and returns a reset pulse. Two 
four-bit keyboxes share one eight-bit 
parallel port, 12 ports for our 24 sta- 
tions. At present we are using three 
Imsai 4PIO boards to provide these. 
Our 24-keyboard installation has 
been in service for over a year. Dur- 
ing this period we have had two 
boxes quit due to off-voltage regula- 
tors. We have had no key failures. 

Numerous keycaps— at least 40 so 
far— have been cracked, due to exces- 
sive force. We find that "key- 
beating" occurs (a) when the system 
is heavily loaded and response is 
slow or (b) when the system has mal- 
functioned. This "kick the machine" 
attitude must be acknowledged by 
any system designer whose machine- 
ry is open to unsupervised use by the 
general public. Be prepared! ■ 



Ken Reid, 1935 Trevilian Way, Louisville, KY 
40205 



Microcomputing, August 1981 151 



Spotting and correcting incorrect data. 



What's the Difference? 



By R. B. Nottingham 



While rereading the November 
1980 issue of Microcomputing, 
my attention was drawn to the wind 
chill temperature program in Robert 
Baker's PET-pourri column (p. 14). 
Suddenly, the antennae of my mem- 
ory began to quiver. I looked closely 
at the data, and it was familiar. I had 
seen it before. Here it was again and 
still wrong! 

How was I able to recognize the 
data, tell that it was wrong by inspec- 
tion, correct it and then amplify it? 
Mathematicians refer to the method 
as difference calculus or the method 
of finite differences. Don't let the ref- 
erence to calculus throw you. You 
can use difference methods if you can 
add and subtract, or tell your micro- 
computer to. 

I have never seen the topic men- 
tioned in the recent Microcomputing 
literature, and I think it is too good a 
tool not to have in your bag of tricks. 
So I'll briefly discuss difference meth- 
ods and then apply them to the prob- 
lem mentioned above. 

Back to Babbage 

About 120 years ago, Charles Bab- 
bage conceived the stored program 
computer with hard-copy output. He 
called his device a difference, or ana- 
lytical, engine. He was concerned 
with the problem of producing error- 
less tables of functions for use in nav- 
igation at sea. He had realized that 
the only way to produce error-free ta- 
bles was to produce them automati- 
cally, without human intervention. 

Babbage realized that you could 



generate any continuous function 
over an interval by simply adding dif- 
ferences. If you look at the squares of 
the integers 1, 4, 9, 16, 25, and at their 
first differences, 3, 5, 7, 9, you'll see 
that their second differences are a 



constant 2. So you can generate a 
table of squares by successively add- 
ing 2 and then successively adding 
these numbers. 

Now try it with cubes. Yes, there is 
a theorem that in a series of this type, 



Address correspondence to R. B. Nottingham, 
1619 SE 3rd Court, Deerfield Beach, FL 33441. 



1 REM DIFFERENCE CALCULUS APPLIED TO WIND-CHILL DATA 

2 REM R. B. NOTTINGHAM, 10-31-80 
60 DIM C(8,ll) 

70 FOR W = TO 8: FOR T = TO 11 

80 READ C(W,T):NEXT T: NEXT U 

90 DATA -60,-50,-40,-30,-20,-10,0,10,20,30,40,50 



100 

110 

120 

130 

140 

150 

16G 

170 

185 

1300 

1010 

1W20 

1030 

1040 

1050 

1060 

1070 

1080 

1090 

1100 

1113 

1120 

1130 

1140 

1150 

1160 

1170 

1180 

1190 

1200 

1210 

1223 

1230 

1240 

1250 

1260 

127C 

1280 

1290 



DATA 
DATA 
DATA 
DATA 
DATA 
DATA 
DATA 
DATA 
GOTO 
FOR 
FOR 



-68,-57,-47,-36,-26,-15,-5,6,16,27,37,48 

-95,-83,-70,-58,-46,-33,-21,-9,4,16,28,40 

-112,-99,-85,-72,-58,-45,-36,-18,-5,11,22,36 

-124,-110,-96,-82,-67,-53,-39,-25,-10,3,18,32 

-133,-113,-104,-88,-74,-59,-44,-29,-15,0,13,30 

-140,-125,-109,-94,-79,-63,-48,-33,-18,-2,13,28 

-145,-129,-113,-98,-82,-67,-49,-35,-20,-4,11,27 

-148,-132,-116,-100,-85,-69,-53,-37,-21,-6,10,26 

1000 



W=l TO 8 
T= 1 TO 11 

PRINT"C(";W;\";T,") = " ; 

PRINTC(WJ), 

IF T=ll THEN GOTO 1110 

D1(T)=C(W,T)-C(W,(T-M)) 

IF T=0 OR T>9 THEN GOTO 1070 

PRINTDl(T) 

IF T<2 OR T>9 THEN GOTO 1110 

D2=D1(T)-D1(T-1) 

PRINT TAB(20)D2 
NEXT T 
PRINT 

INPUT"pRESS ENTER TO CONTINUE" ;QQ 
NEXT W 

FOR T=0 TO 11 
FOR W«l TO 8 

PRINT"C(";W;","J,") = \ 

PRINTC(WJ); 

IF W=8 THEN GOTO 1250 

D1(W)=C(W,T)-C(W+1,T) 

PRINTDl(W) 

IF W<2 OR W>6 THEN GOTO 1250 

D2=D1(W)-D1(W-1) 

PRINTTAB(20)D2 
NEXT W 
PRINT 

INPUT"PRESS ENTER TO CONTINUE", 
NEXT T 
END 

Program listing. 



152 Microcomputing, August 1981 



the difference which becomes con- 
stant is the power of the series. 
Squares, second difference; cubes, 
third difference, and so on. 

This is a useful tool. If you have a 
function— the flight of a model rock- 
et, the landing path of an airplane or 
whatever— that you want to show on 
your computer, it may make much 
better sense to store the equation of 
the curve and calculate it as you need 
it, rather than store all the data of the 
curve itself. If you examine the suc- 
cessive differences in the data, and 
you find that some difference tends 
to become a constant, that gives the 
order of the polynomial that will be 
needed to fit the data. 

Wind Chill 

Now regarding wind chill. I had 
found an article on the subject sever- 
al years ago in a bicycling magazine, 
giving the same data which Baker 
used. If you do not have his program 
handy, lines 60-170 in Listing 1 are 
copied directly from it. The data in 
line 90 represents Fahrenheit tem- 
peratures from - 60 to + 50. 

The lower temperatures are a little 
exotic unless you plan to wing-walk 
at high altitudes or visit the poles. 
Plus 50 was not quite high enough to 
suit me. It is rarely that cold in south 
Florida, and believe it or not, when 
one is acclimated here, riding a bike 
with the temperature in the 60s can 
feel chilly, particularly if the sun isn't 
shining. So I decided to extend the ta- 
ble up to 70 or 80 degrees, perhaps 
discarding the very low temperatures. 

Line 100 gives the wind chill for a 
five mph wind, and successive lines 
increase the speed in increments of 
five mph. Comparing line 90 and line 
100, from right to left, you see that 
the wind chill increases as the air 
temperature gets lower. Reasonable 
enough. If you read down any col- 
umn, you'll see that the increase in 
wind chill gets less as the wind speed 
increases. The increases from 35 mph 
to 40 mph (lines 160, 170) are very 
small. Apparently, once the wind 
speed is high enough to carry away 
all our body heat, more wind doesn't 
make much difference. 

Now, if you look at the differences 
I along any line, the wind chill seems 
to increase about 10 or 15 degrees for 
every ten-degree change in tempera- 
ture. But look at the right end of line 
120. The differences are 14, 11, 16, 
13, etc. There is no way that the dif- 
ferences can jump around like this. 



As our German friends don't say, 
"Etwas ist gestunken." 

Apparently, the wrong table has 
been copied and copied with no ref- 
erence to the original. Errors have 
crept in and have propagated. So 
what do we do about it? 

Since you have a microcomputer, 
you might as well put it to work. If 
you have the Baker Wind-Chill pro- 
gram loaded, just add line 185 from 
Listing 1, and lines 1000-1160. Do 
not add line 2120. It is simply my ap- 
proximately corrected version of line 
120. You may well be able to do bet- 
ter. 

Now run the program; you will see 
the original data and the first and sec- 
ond differences, first along the rows, 
and then down the columns. Obvi- 
ously there is trouble. What you want 
to do is make the differences uni- 
form. When you find a difference 
you don't like, press the break key. 

Then, in the direct mode, enter 
C(W,T)=X, replacing W,T and X 
with the appropriate values. Type 
GOTO 1000. Do not type RUN or the 
variables will be set to zero. Repeat 
this until the differences please you 




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and then correct the DATA state- 
ments. If you have a printer, you 
may, of course, LLIST the array for 
your new data. 

If you wish to extrapolate the table 
to higher temperatures, this is easy to 
do, if you watch the differences. For 
example, at five mph, it looks like the 
difference at 60 degrees will be either 
one or two degrees, and at 70, one 
degree. 

At 40 mph, the difference is run- 
ning about 16 degrees, so you might 
make the wind-chill temperature for 
60, 42 degrees, and for 70, about 67 
degrees. If you keep the differences 
smooth you won't be far off, even 
though extrapolation (going out be- 
yond the original data) is always dan- 
gerous. A function may be discontin- 
uous, but I would be very surprised if 
wind chill were. If you add tempera- 
tures to each data line, be sure to 
either delete temperatures at the left 
of the line, or revise the dimensions 
of the arrays. 

Have fun. I think that the method 
of differences is a useful tool, and just 
thinking in terms of differences can 
often let you spot bad data.B 



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Microcomputing, August 1981 153 



Quick, bug-free, and well worth the price. 



TSC Extended BASIC 



By Phil Hughes 



TSC Extended BASIC (Technical 
Systems Consultants, PO Box 
2570, W. Lafayette, IN 47906) is an 
excellent product for the 6800 and 
6809 microprocessors. It has the abil- 
ities of a comprehensive BASIC, is 
well-documented and relatively bug- 
free. If you are running Flex and need 
a BASIC with these capabilities, it is 
well worth its price. It costs $100, 
configured for either five- or eight- 
inch disks. 

In spite of the comprehensive addi- 
tions, TSC Extended BASIC is fast. 
Table 1 shows comparison times for 
the fastest BASIC (OSI), Altair ex- 
tended BASIC and the other two 6800 
BASICs. These times are for running 
Tom Rugg's and Phil Feldman's 
benchmark programs that appeared 
in the June 1977 issue of Kilobaud 
("BASIC Timing Comparisons," p. 

66). 

Note that OSI BASIC was run on a 
system that could not support disk 
drives because the clock speed was 
doubled. The first TSC Extended BA- 
SIC test ran with the benchmarks ex- 
actly as written. The second line 
shows timing information when the 
control variables in the FOR-NEXT 
loops were changed to integer data 
type. 

Extensions 

Now that you know that this BA- 
SIC is competitive in speed, let's look 
at the extensions in detail. First con- 
sider the extensions to variables and 
operators. Variable names have been 



extended to allow two alphabetic 
characters, as well as the standard al- 
phabetic and alphabetic followed by 
a numeric. For example, AB is a valid 
variable name, as are A and Al. This 
is important because it is easier to 
imagine that ST stands for subtotal 
than S or S7. 

Note that there are seven two-letter 
combinations that are keywords and 
therefore cannot be used as variable 
names. They are AS, FN, IF, ON, OR, 
PI and TO. 

The other big addition to variables 
is the integer data type. These vari- 
ables may be mixed with floating 
point (real) variables, and will save 
both execution time and storage 
space. They are particularly useful 
for loop control variables and array 
subscripts. 

Their range is from -32768 to 
32767 and they take only two bytes of 
storage. Compare this with eight 
bytes for a floating point variable. An 
integer variable is identified by the 
suffix %. For example, 

FOR 1% = 1 TO 100:NEXT 1% 

is a loop with the integer control vari- 
able 1% . 

New operators consist of the logical 
operators AND, OR and NOT and the 
string concatenation operator, +. 
The logical operators operate on inte- 
gers in a bit-by-bit fashion. If the ar- 
guments of a logical operator are real 
variables, they are automatically con- 
verted to integers before the opera- 
tion is performed. Also, if the real 



variables have too large a value for 
conversion, an error message is 

printed. 

The next group of new features, 
statement extensions, is added to ex- 
isting BASIC statements. The first of 
these is an addition to the RESTORE 
statement which lets you specify the 
statement number to which the data 
pointer should be reset. This would 
have saved me some time when I 
converted WUMPUS 2 to run on the 
SWTP system in 1977. 

Next, and definitely more impor- 
tant, is the addition of the ELSE 
clause to the IF statement. In a sen- 
tence, this allows you to write a state- 
ment with the form 

IF condition THEN do this ELSE do something 
else 

INPUT LINE lets you read an en- 
tire line of input, including spaces, 
punctuation and quotes, into a single 
string variable. This is very useful 
when you are trying to make pro- 
grams easy for the naive user. PRINT 
USING is a very important feature 
for business programming. This 
statement lets you format your out- 
put as you wish, overriding the auto- 
matic zoning of BASIC. 

Although it's hard to think of PEEK 



Phil Hughes (PO Box 2847, Olympia, WA 98507) 
owns Specialized Systems Consultants, a computer 
hardware/software consulting company. 



154 Microcomputing, August 1981 



Hardware/Software 


CPU 


12 3 4 5 


6 


7 


LOSI8K BASIC @2MHz 


6502 


.9 4.6 8.2 9.3 10.0 


14.8 


21.6 


10. Altair Disk Extended BASIC 


8080 


1.9 7.5 20.6 20.9 22.1 


36.9 


58.5 


28. Southwest Tech 8K BASIC 1.0 


6800 


14.9 24.7 96.1 105.3 109.8 


174.1 


204.5 


* * * TSC Extended BASIC 


6800 


1.2 4.4 19 21.5 22 


29 


38.5 


* * * TSC Extended BASIC 


6800 


.4 2.9 7.5 7.5 8 


12 


20.5 


w/integer control variables 










Table 1. Comparison times ft 


)r standard and extended BASICs. 







and POKE as extensions anymore, 
they are included. With the capabili- 
ty of the HEX function (see functions) 
they are somewhat more usable. 

Two new statements that seem to 
fit into this same group are DIGITS 
and SWAP. The DIGITS statement 
specifies the maximum number of 
digits that are to be printed in an an- 
swer. This is independent of PRINT 
USING. DIGITS is useful for those of 
us with a background in mathematics 
who know how absurd it is to tell 
someone that the average of 13, 55, 
97, 87, 66, 90, 94, 64 and 45 is about 
67.888888888888891. 

SWAP is useful for speeding up 
sorts. It switches the values of two 
variables in one step. It is particularly 
useful with string variables, where it 
changes the contents of two four-byte 
string descriptors rather than moving 
the actual data strings. 

The next category of extensions is 
functions. The standard mathemati- 
cal functions exist with 16-digit accu- 
racy for LOG, EXP and SQR, and 13- 
1/2-digit accuracy for ATN, COS, SIN 
and TAN. There is also a full set of 
strirg-to-integer, integer-to-string and 
substring handling functions. 

The substring function least likely 
to exist in other BASICs is INSTR, the 
equivalent of the PL/1 function, IN- 
DEX. This function will search a 
specified string, starting at a given po- 
sition, and return the location of a 
specified substring. This function, 
along with INPUT LINE, makes an 
excellent tool for fancy input han- 
dling routines. 

Another important function is HEX, 
which converts a string of up to four 
characters into an integer with an 
equivalent value. For example, you 
can write HEX ("8000") instead of 
32768. 

System Interface Extensions 

The system interface extensions ex- 
ist at the command level of BASIC, 
and let you communicate with the 
operating system. Note that some of 

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these capabilities may also be used 
within statements. The standard ones 
are RUN, LIST, CONT, LOAD, SAVE 
and NEW. TSC Extended BASIC of- 
fers a whole lot more. 

The first one is COMPILE. This lets 
you save a BASIC program on disk in 
a compiled form. In this form the pro- 
gram uses less disk space, and there- 
fore will load faster than its source. 
At execution time a source or com- 
piled program will run at essentially 
the same speed. Also, a compiled pro- 
gram cannot be listed or edited. This 
gives you a method of releasing exe- 
cutable programs to others without 
making the source available. 

TRON and TROFF allow you to 
turn on and off the line number trace. 
This is not very useful, since you can- 
not embed TRON and TROFF state- 
ments in your program and therefore 
must trace everything. SCALE allows 
you to force the roundoff of floating 
point numbers. In early BASICs, it 
was quite common to get .999999 as 
the result of dividing 10 by 10. This 
BASIC takes care of its own roundoff 
problems, but SCALE is there if you 
have a special case. One special case 
is, of course, rounding off dollars and 
cents to even pennies. 

RENUMBER is actually a program 
that is loaded into the utility com- 
mand space of Flex. It comes with 
BASIC, works very fast and renum- 
bers lines in the currently loaded BA- 
SIC program. It's about time BASIC 
came with this important feature. 

KILL and RENAME allow you to 
delete and rename disk files. Both of 
these commands can also appear in 
statements. This lets you handle file 
maintenance within the BASIC pro- 
gram. CHAIN, another system inter- 
face command that can appear in a 
program statement, allows you to 
load and start execution of a new pro- 
gram. CHAIN also lets you specify 
the line number where execution is 
to begin. 

In addition to these specific BASIC 
commands, any Flex command that 



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loads into the utility command space 
can be executed by preceding its 
name with a plus sign ( + ). Through 
this method CAT (catalog list), TTY- 
SET (configure terminal characteris- 
tics) and many other commands can 
be accessed. The BASIC statement 
EXEC permits access from within a 
program. Don't try +NEWDISK; al- 
though it loads into the UCS, it ap- 
pears to use low memory for an I/O 
buffer, and you never hear from BA- 
SIC (or anything else until you push 
RESET) once you start it. 

Advanced Disk Capabilities 

TSC devotes 14 pages of the user's 
manual to advanced disk capabilities, 
but even with this much information 
you may spend a lot of time rereading 
and testing to get the hang of it. I can 
only let you know the capabilities are 
there— plan to spend some time get- 
ting to know how to use them. 

All of these capabilities have to do 
with random access disk files. The 
first one, virtual arrays, consists of an 
array (dimensioned variable) stored 
in a disk file instead of RAM. It can 
be used just like any other array, with 
a few exceptions. A reference to an 
element of the array causes an auto- 
matic read from, or write to, disk. 
The reference is considerably slower 
than if the element had been in RAM, 
but much larger arrays can be han- 
dled. 

Now the exceptions. All elements 
of a string virtual array must be the 
same length. The maximum length of 
a string element in a virtual array is 
252 bytes (vs 32767 for ordinary string 
arrays). The third exception is that 
values in a virtual array cannot be 
displayed using PRINT if a program 
has terminated in error. Although, 
initially, this third exception seems 
like a severe handicap in debugging, 
it can be sidestepped by using the ON 
ERROR and STOP statements. 

The second type of random I/O is 
Record I/O, which allows you to read 
or write any sector within a disk file. 
These sectors correspond to physical 
disk sectors, which consist of 252 
data bytes and four Flex header bytes. 
A read is performed by the GET state- 
ment, and a write is performed by the 
PUT statement. This is the basis for 
Record I/O; everything else is just a 
set of tools to make it easier to use. 

The first tool is the FIELD state- 
ment. FIELD allows you to assign 
string variable names to parts of the 
252-byte buffer which is used by 
GET and PUT. Two other tools, LSET 



and RSET, allow you to store data in 
the portions of the buffer described 
by the FIELD statements. The four 
tools completing the available set are 
conversion routines which convert 
integers and floating point numbers 
to and from strings. These are neces- 
sary because Record I/O files contain 
only characters. 

Using these tools, you can describe 
records consisting of specified fields 
of data, and read and write these rec- 
ords. If these records are 252 bytes in 
length, then a record is a sector and 
everything goes smoothly. 

To handle records less than 252 
bytes, you must either waste disk 
space or pack multiple records into a 
single sector. Packing can be done 
with the FIELD statement, but it 
takes a lot of the pleasure out of hav- 
ing this type of I/O. In a sentence, it 
isn't elegant but it does the job. 

Now that you know what Record 
I/O is, you can see that it makes doing 
inventory systems and the like feasi- 
ble. Using Record I/O for data files 
and virtual arrays for indexes, you 
will find that inverted key (look up 
by more than one thing) file access 
systems become practical. For exam- 
ple, you can look up an entry in an 
address list by either last name or ZIP 
code. 

Some Problems 

Bug-wise, the version that I have 
(version 8) is a very stable product. 
This is the third version that I have 
had, but TSC was very cooperative in 
sending updated versions in response 
to my documented problems. The on- 
ly remaining problem that I find irri- 
tating is that certain errors in a pro- 
gram cause the LOAD command to 
terminate without loading the entire 
file. Actually, the irritating part is 
that no error message is issued. This 
only occurs on files which have been 
created by the editor or another BA- 
SIC. TSC Extended BASIC will not al- 
low you to enter lines that cause this 
error. 

I have two other complaints. First, 
extended BASIC is very big— a little 
over 18K. For the features available, 
the size is not excessive, but you may 
have to justify the cost of that new 
16K memory board along with the 
cost of BASIC. And the documenta- 
tion on extended BASIC, like most 
other TSC documentation, is hard to 
use. I don't know why this is, but my 
customers have the same problem. 
All of the information is in the man- 
ual— it's just hard to find.B 



156 Microcomputing, August 1981 



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Microcomputing, August 1981 157 



This TRS-80 program helps you get the most out of your resources. 



How to Maximize Profits 



By James R. Burns 



A dentist is faced with deciding 
how best to split his practice be- 
tween the two services he offers- 
general dentistry and pedodontics 
(children's dental care). Given his re- 
sources, how much of each service 
should he provide to maximize his 
profits? 

He can find the answer with the 
help of a process known as mathe- 
matical programming (MP). This is 
not programming in the computer 
sense of the word, but instead refers 
to a specific set of mathematical pro- 
cedures used to solve a problem. 

Every mathematical programming 
problem consists of a goal and a set of 
constraints. For the business manag- 
er, the goal is to find a product mix 
that will realize the greatest net re- 
turn. The constraint is that the re- 
sources he can allocate to his prod- 
ucts or services are limited. These re- 
sources might include money, man- 
hours, machine capacities or ware- 
house space. 

Since the computer can do the com- 
putational work, a manager need not 
be a mathematician to use MP suc- 
cessfully. What he must be able to do, 
however, is 1) recognize when MP is 
an appropriate method to use, 2) 
formulate the problem so that it can 
be solved (by the computer) and 3) in- 
terpret the results and use them cor- 
rectly. 

A Resource Allocation Problem 

The dentist mentioned above em- 
ploys three assistants and uses two 
operatories (work stations). Each pe- 
dodontic service requires .75 hours 



James R. Burns (3204 80th St., Lubbock, TX 79423) 
is an associate professor at Texas Tech University 
and president of Software Engineering Systems, Inc. 



of operatory time, 1.5 hours of an as- 
sistant's time and .25 hours of the den- 
tist's time. A general dentistry service 
requires .75 hours of an operatory, 1 
hour of an assistant's time and .5 
hours of the dentist's time. Net profit 



for each service is $10 for each pedo- 
dontic service and $7.50 for each gen- 
eral dental service. Since the dentist's 
office is open eight hours a day, there 
are eight hours of dentist's time each 
day, 16 hours of operatory time, and 



Listing 1. Mathematical programming in TRS-80 Level II BASIC. 

10 CLS:CLEhR500:F : RINTSTRING»':&3. 191) : PR I NT #83, "MRV1MI7F YOUR PROFITS* IPRINTSTRIN 

G»(63, 149; 

20 PRINTTRB( 23 ;"JRME3 R. BURNS 11 

30 PRINTTRBt 15; "SOFTWARE ENGINEERING SYSTEMS, INC." 

40 PRINTTRB<22)*3204 801 H STREET" 

50 PRINTTRBC 21 ) "LUBBOCK, TEXRS 79423" 

50 FORIX=l TO20:PRINT»448, STRING** 63, 191 ): PRINT $448, STRINGS* 63, 149>:NEXTI5t 

70 * 

B0 ENTER NUMBER OF URRIRBLES RND NUMBER OF CONSTRR1NTS 

90 ' 

100 INPUT "WHRT IS THE NUMBER OF PRIMRL URRIRBLES" ; N?£ 

110 INPUT "WHRT IS THE NUMBER OF CONSTRRINTS" ; M5i 

120 EX-1:LX-MX+EV.KX-NX+LX 

130 DIMTR(LX,KX),RR(MX) 

140 ' 

150 ' DEFINE CONSTRR1NT COEFFICIENTS 

160 ' 

170 FORIX-EXTOMX 

180 FORJX=EXTONX 

190 PRINT "COEFFICIENT OF URR1RBLE " ; JX; ' IN CONSTRRINT* ; IX; 

200 INPUT " IS* ; TA( IX, JX): NEXT JX 

210 PRINT"RMOUNT OF RESOURCES IN CONSTRR INT " ; IX; 

220 INPUT" IS";TR( IX,KX):TR( IX, NX+IX )-EX: NEXTIX 

230 ' 

240 ' DEFINE OBJECTIUE FUNCTION COEFFICIENTS 

250 ' 

260 FORJX-EXTONX 

270 PRINT-WHfiT IS THE COEFFICIENT RSSOCIRTED WITH URRIRBLE* ; JX; " IN THE" 

280 INPUT "OBJECTIUE FUNCTION* ; TRC LX, JX ) 

290 TR( LX , JX )=-TR< LX , JX ) : NEXT JX 

300 INPUT"DO YOU WISH THE TRBLERU PRINTED RFTER EUERY ITERRTION--Y/N* ; T» 

310 ' 

320 ' BEGIN SIMPLEX ITERRTIONS HERE 

330 ' 

340 ' PICK THRT COLUMN WITH THE MOST NEGRTIUE "INDICRTOR" RS THE NEXT 

350 ' URRIRBLE TO ENTER THE BRSIS. STRP.T WITH ONLY SLRCK 

360 ' URRIRBLES IN THE INITIRL BRSIS. 

370 ' 

380 GOSUB930 

390 MI-1E30 

400 KORQX=EXTONX+MX 

410 1FMK = TRCLX,OX)THEN440 

420 MI=TR(LX,OX) 

430 JX-GX 

440 NEXTOX 

450 IFMI >-01HEN820 

460 ' 

470 R COLUMN < JX ) WITH THE MOST NEGRTIUE INDICRTOR HRS BEEN FOUND 

480 ' 

490 FORIX-EXTOMX 

500 * 

510 ' FIND THE ROW WHOSE RRTIO IS SMRLLEST POSITIUE. RSSOCIRTED 

520 URRIRBLE IS EXITING BRSIS URRIRBLE. 

530 * 



158 Microcomputing, August 1981 



Z4 hours ot assistants time each day. 

The objective is to divide each eight- 
hour day between general practice 
and pedodontics in such a way as to 
maximize profit. Let x x represent the 
number of pedodontic patients seen 
per day and x 2 the general dentistry 
patients seen per day. Then the objec- 
tive function for this problem is ex- 
pressed by 10xi + 7.5x 2 . 

The constraints are the total hours 
available for each of the three re- 
source categories— dentist's time, op- 
eratory time and assistants' time. 
Eight hours are available to the den- 
tist. Each pedodontic service requires 
(as stated) .25 hours of the dentist's 
time, and each general practice, .5 
hours. The total time devoted to these 
two categories is .25x! + .5x 2 . Since 
this must be less than or equal to eight, 
the constraint is written 

.25xi + .5x 2 <8 (dentist's time) 

The remaining two constraints are 
written 



Formulating an MP problem begins with an identification 
of the resources and the products or services. 



1.5xi+x 2 <24 (assistants' time) 
.75xx + .75x 2 <16 (operatory time). 

In total the problem as formulated 
is 

maximize 10xi + 7.5x 2 

subject to 

.25xi + .5x 2 <8 dentist 
1.5xi +x 2 <24 assistants 
.75Xi + .75x 2 <16 operatories. 

How to Formulate an MP Problem 

As the example above shows, the 
task of formulating an MP problem 
begins with an identification of the 
resources and the products or ser- 
vices. For each product or service, a 
variable x } is defined. Then the objec- 
tive is written in the language of 
mathematics as a statement of the 



540 IFTRdX, JXK1E-10THENRRC IX )«1E35: GOTO560 

550 RR( 1X)=TR( IX,KX)/TRt IX, JX ) 

560 NEXT IX 

570 MI-1E35:INX=100 

580 FORIX=EXTONX 

550 IFRRC IX ) >~niORRfl< IX )< -0THEN610 

600 MI=RR( IX): INX^IX 

610 NEXT IX 

620 IFINX=100THENPRINT"SOLUTION UNBOUNDED* : END 

630 DI=TR( INX, JX) 

640 1 ORIX=EXT0KX 

650 TR( INX, 1X)=TRC INX, lX)/Iil 

660 NEXT I % 

670 FORRX-EXTOLX 

680 1FRX-INXTHEN760 

6^0 • 

700 ' BEGIN PIUOT HERE 

710 ' 

720 I1U=TR(RX,JX) 

730 FORIX-EXTOKX 

740 TR(RX, IX)=TR(RX, IX }-MU*TR< IN* , IX) 

750 NEXT IX 

760 NE.\TRX:GOSUB990 

770 GOTO390 

730 ' 

790 ' SOLUTION HRS BEEN FOUND R5 THERE RRE NO COLUMNS WITH NEGATIVE 

800 INDICATORS. RESULTS RRE PRINTED IN THE STRTEMENTS THRT FOLLOW. 

810 

620 CL5:PRINT*MRXIMUM OBJECTIVE FUNCTION URLUL IS - : TR( LX, KX ) 

630 FORJX-EXTONX 

840 IFTRCLX, JXV>0.THEN880 

850 FORIX=EXTOMX 

860 1F.999<TR( IX, JX JRNDTRC IX, JXK 1 . 001THENPRINT*MRXIMUM URLUE FOR URRIRBLE ■ ; IX', 

IS" ;TR( IX, KX J-.GOTO880 
870 NEXT IX 
880 NEXTJX 

B«EM» 1NRVJT-H1T ENTER TO SEE SHRDOW PRICES- -OK "; XX 

900 CLSt PRINT "SENSITIVITY COEFFICIENTS ( DURL URRIRBLES) RRE" 

910 FORIX-CXTOMX 

92(0 PRINT 1RB(20)TR(LX,NX+IX) 

930 NLX1 IX 

940 INPUT *HIT EiNTER TO END"; XX 

950 END 

960 ' 

970 ' ROUTINE TO PRINT SIMPLEX TRBLERU 

900 ' 

990 IFT*< ; *Y*THENRFTURN 

1000 FORUX-EXTOLX 

1010 PRINT "ROW" ; UX; STRINGS' 1 . 170 ) ; 

1020 FORVX-EXTOKX 

1030 PR I NT T R ( UX , UX ' ; 

1040 NEXTUX 

1050 PRINT 

1060 NEXTUX 

1070 INPUT HIT ENTER TO RETURN- -OK "; XX 

1080 RETURN 



profit potential for a given time peri- 
od. Each Xj variable is multiplied by 
the net profit accruing from the sale 
of just one unit of the product or ser- 
vice. 

In the problem above, $10 of profit 
is realized from each pedodontic (pa- 
tient) service. If five such services 
were provided in any given day, then 
$50 of profit would accrue from 
pedodontic services alone. Similar 
statements could be made about gen- 
eral dentistry services. Hence, total 
profit is the sum of the individual 
profits arising from the provision of 
these two services. 

Once the objective is formulated, 
the constraints are written. Each con- 
straint expresses the resource re- 
quirements for a particular product 
mix. The total resource requirement 
must be less than or equal to the total 
amount of resource available for a 
particular resource. Mathematically, 
this is written as an inequality. In the 
problem posed above, there are three 
resources, and therefore three in- 
equalities. In addition to these in- 
equalities, the Xj variables must be 
non-negative. (A negative value for Xi, 
the number of hours devoted to pedo- 
dontic services, has no meaning; sim- 
ilarly for x 2 .) 

How to Use the Computer 
Program 

The computer program shown in 
Listing 1 can be used to solve this 
problem. As listed, the program is 
ready to run on a TRS-80 Level II ma- 
chine. Some modification may be re- 
quired for other machines. The pro- 
gram uses the simplex method of so- 
lution and is able to detect when the 
problem is unbounded. Appropriate 
responses to the queries posed by the 
program for the problem described 
above are shown in Sample la. 

User responses appear to the right 
of each query (which ends with a 
question mark). The queries request 
the number of variables and con- 
straints, followed by all coefficients 
in the constraints and in the objective 
function. Array dimensions and slack 
variables are taken care of automati- 
cally by the program and do not re- 
quire user attention. To properly en- 
ter responses to the queries you must 
define (for yourself) the variables, ob- 



Microcomputing, August 1981 159 



WHAT IS THE NUMBER OF PRIMAL VARIABLES? 2 

WHAT IS THE NUMBER OF CONSTRAINTS? 3 

COEFFICIENT OF VARIABLE 1 IN CONSTRAINT 1? .25 

COEFFICIENT OF VARIABLE 2 IN CONSTRAINT 1? .5 

AMOUNT OF RESOURCES IN CONSTRAINT 1? 8 

COEFFICIENT OF VARIABLE 1 IN CONSTRAINT 2? 1.5 

COEFFICIENT OF VARIABLE 2 IN CONSTRAINT 2? 1 

AMOUNT OF RESOURCES IN CONSTRAINT 2? 24 

COEFFICIENT OF VARIABLE 1 IN CONSTRAINT 3? .75 

COEFFICIENT OF VARIABLE 2 IN CONSTRAINT 3? .75 

AMOUNT OF RESOURCES IN CONSTRAINT 3? 16 

WHAT IS THE COEFFICIENT ASSOCIATED WITH VARIABLE 1 IN THE OBJECTIVE 

FUNCTION? 10 

WHAT IS THE COEFFICIENT ASSOCIATED WITH VARIABLE 2 IN THE OBJECTIVE 

FUNCTION? 7.5 

DO YOU WISH THE TABLEAU PRINTED AFTER EVERY ITERATION-Y/N? N 

Sample la. 



OPTIMUM ANSWER IS 170 

MAXIMUM VALUE FOR VARIABLE 1 IS 8 

MAXIMUM VALUE FOR VARIABLE 2 IS 12 

HIT ENTER TO SEE SHADOW PRICES-OK? 

SENSITIVITY COEFFICIENTS (DUAL VARIABLES) ARE 

2.5 

6.25 


HIT ENTER TO END? 

Sample lb. 



jective function, constraints and coef- 
ficients that are needed in the MP 
model. From the responses entered 
in Sample la it should be clear that 
the following conventions were used: 

•variable 1— x it pedodontic patients 
seen per day 

• variable 2— x 2 , general dentistry 
patients seen per day 

• constraint 1— dentist's time per day 

• constraint 2— assistants' time per 
day 

• constraint 3— operatory time per 

day. 

Once computations required by the 
simplex algorithm are complete, the 
reports in Sample lb are printed. 

Clearly the optimum (maximum) 
objective function value is $170 dai- 
ly. The dentist should see eight pedo- 
dontic patients per day and 12 gener- 
al dentistry patients per day. In addi- 
tion to the above reports the program 
will also print the simplex tableau af- 
ter each iteration if you respond with 
"Y" to the last query in the sequence. 
It is easy to verify that when (8, 12) 
replaces (xi, x 2 ) in the objective func- 
tion, a value of 170 is realized— i.e., 
10x8-1-7.5x12=170. Also, it is easy 
to verify that all of the dentist's time 



per day and all of the assistants' time 
per day are used up by the combina- 
tion (8,12). 

Sensitivity Studies 

The sensitivity coefficients indicat- 
ed in Sample lb tell how sensitive the 
optimum answer (objective function 
value) is to changes in the resource 
value associated with each constraint. 
Thus, the resource associated with 
constraint 1 (dentist's time) has a sen- 
sitivity value of 2.5, the resource as- 
sociated with constraint 2 (assistants' 
time) has a sensitivity value of 6.25, 
and so on. Since there are three con- 
straints in the problem, three sensi- 
tivity coefficients are printed. 

Obviously, the answer is most sen- 
sitive to changes in the assistants' 
time resource. In fact, one unit of in- 
crease in this resource will produce 



6.25 additional units of profit in the 
objective function. Our hypothetical 
dentist would be well-advised to add 
extra hours of dental assistants' time 
per day; it is the resource that should 
be increased first. 

A Portfolio Selection Problem 

Resource allocation problems are 
not the only MP problems solvable 
by the program in Listing 1 . The pro- 
gram can also be used to solve portfo- 
lio-selection problems, as typified by 
the following. 

A stockbroker has been asked by a 
client to invest a sizeable sum of 
money in a portfolio of common 
stocks. The overall objective is to 
maximize the growth of capital. 
However, the portfolio is not to ex- 
ceed a prescribed degree of risk. Al- 
so, the portfolio must provide at least 
enough income to pay for taxes and 
other expenses. 

The stockbroker has available to 
him information on a large number of 
companies, broken down into vari- 
ous industry groups. Each company 
is rated on a scale of to 9 for its 
growth and risk potential, where in- 
dicates no growth or no risk and 9 in- 
dicates highest growth or highest 
risk. No more than 35 percent of the 
portfolio is to be invested in any one 
industry group. The risk factor can- 
not exceed 10. The information about 
the companies is given in Table 1. 

Let Xj represent the fraction of the 
portfolio to be invested in company i. 
Then the MP problem can be formu- 
lated in accordance with the remarks 
made above as follows: 

maximize 7x! + 2x 2 + 8x 3 + 9x4 + 3x 5 + 6xe + 7x 7 + 
8xa + 6x 9 + 4x 10 + 3xx ! + 4x 12 + 8x 13 + 8x u + 8x 15 + 
9x 16 

subject to 

3xi + 6x 2 + 5x 3 + 8x4 + x 5 + 5xe + 7x 7 + 2xg + x 9 + 
4xio + 5xi 1 +6xi2 + 9x 13 + 7x 1 4 + 8x 15 + 7xi 6 <10 

X! + X 2 + X 3 + X4 + X 5 + Xe + X 7 + Xg + X 9 + X10 + x n + 
X12 + X 13 + X 14 + X15 + X 16 < 1 

Xi+x 2 + x 3 + X4<.35 

X5+X6 + X 7 + X8<.35 

x 9 + X10 + Xi 1 + Xi2<.35 

X13 + X14 + X15 + Xib^.oo 

In all, this problem has 16 variables! 
and six constraints. The first con-l 
straint relates to risk. The second! 



Industry 


A 


B C 


D 


Company 


12 3 4 


5 6 7 8 9 10 11 12 


13 14 15 16 


Growth 


7 2 8 9 


3678 6434 


8 8 8 9 


Risk 


3 6 5 8 


13 7 2 14 5 6 
Table 1. 


9 7 8 7 



160 Microcomputing, August 1981 




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Microcomputing, August 1981 161 



WHAT IS THE NUMBER OF PRIMAL VARIABLES? 16 
WHAT IS THE NUMBER OF CONSTRAINTS? 6 
COEFFICIENT OF VARIABLE 1 IN CONSTRAINT 1 IS? 3 
COEFFICIENT OF VARIABLE 2 IN CONSTRAINT 1 IS? 6 
COEFFICIENT OF VARIABLE 3 IN CONSTRAINT 1 IS? 5 
COEFFICIENT OF VARIABLE 4 IN CONSTRAINT 1 IS? 8 
COEFFICIENT OF VARIABLE 5 IN CONSTRAINT 1 IS? 1 
COEFFICIENT OF VARIABLE 6 IN CONSTRAINT 1 IS? 5 
COEFFICIENT OF VARIABLE 7 IN CONSTRAINT 1 IS? 7 
COEFFICIENT OF VARIABLE 8 IN CONSTRAINT 1 IS? 2 
COEFFICIENT OF VARIABLE 9 IN CONSTRAINT 1 IS? 1 
COEFFICIENT OF VARIABLE 10 IN CONSTRAINT 1 IS? 4 
COEFFICIENT OF VARIABLE 1 1 IN CONSTRAINT 1 IS? 5 
COEFFICIENT OF VARIABLE 12 IN CONSTRAINT 1 IS? 6 
COEFFICIENT OF VARIABLE 13 IN CONSTRAINT 1 IS? 9 
COEFFICIENT OF VARIABLE 14 IN CONSTRAINT 1 IS? 7 
COEFFICIENT OF VARIABLE 15 IN CONSTRAINT 1 IS? 8 
COEFFICIENT OF VARIABLE 16 IN CONSTRAINT 1 IS? 7 
AMOUNT OF RESOURCES IN CONSTRAINT 1 IS? 10 
COEFFICIENT OF VARIABLE 1 IN CONSTRAINT 2 IS? 1 
COEFFICIENT OF VARIABLE 2 IN CONSTRAINT 2 IS? 1 
COEFFICIENT OF VARIABLE 3 IN CONSTRAINT 2 IS? 1 
COEFFICIENT OF VARIABLE 4 IN CONSTRAINT 2 IS? 1 
COEFFICIENT OF VARIABLE 5 IN CONSTRAINT 2 IS? 1 
COEFFICIENT OF VARIABLE 6 IN CONSTRAINT 2 IS? 1 
COEFFICIENT OF VARIABLE 7 IN CONSTRAINT 2 IS? 1 
COEFFICIENT OF VARIABLE 8 IN CONSTRAINT 2 IS? 1 
COEFFICIENT OF VARIABLE 9 IN CONSTRAINT 2 IS? 1 
COEFFICIENT OF VARIABLE 10 IN CONSTRAINT 2 IS? 1 
COEFFICIENT OF VARIABLE 1 1 IN CONSTRAINT 2 IS? 1 
COEFFICIENT OF VARIABLE 12 IN CONSTRAINT 2 IS? 1 
COEFFICIENT OF VARIABLE 13 IN CONSTRAINT 2 IS? 1 
COEFFICIENT OF VARIABLE 14 IN CONSTRAINT 2 IS? 1 
COEFFICIENT OF VARIABLE 15 IN CONSTRAINT 2 IS? 1 
COEFFICIENT OF VARIABLE 16 IN CONSTRAINT 2 IS? 1 
AMOUNT OF RESOURCES IN CONSTRAINT 2 IS? 1 

Sample 2a. 



constraint merely states the fact that 
all fractions must sum to 1. The third, 
fourth, fifth and sixth constraints 
stipulate that no one industry can 
represent more than 35 percent of the 
portfolio. 

To enter this problem the user must 
respond to roughly 100 queries, a 
portion of which is provided in Sam- 
ple 2a. 

The outputs produced by the pro- 
gram in Listing 1 are shown in Sam- 
ple 2b. 

These outputs suggest that 35 per- 
cent of the portfolio should be invest- 
ed in company 4, 30 percent in com- 
pany 8 and 35 percent in company 
16. Maximum return from this port- 
folio is 8.7. The sensitivity coeffi- 
cients suggest that the second con- 
straint is the one to which the maxi- 
mum objective function value is most 
sensitive. However, the right-hand- 
side value of this constraint cannot be 
increased. The third and sixth con- 
straints also influence the objective 
function value, as indicated by the 



third and sixth sensitivity coefficient 
values above. 

Epilogue 

The program shown in Listing 1 is 
able to solve maximization problems 
with < inequalities. Two such prob- 
lems were solved in this article. How- 
ever, MP problems can also be mini- 



mization problems and can involve > 
inequalities and equalities. One of 
the three programs in the Mathemati- 
cal Programming System offered by 
Software Engineering Systems is able 
to solve this more general class of 
problems. The program uses the sim- 
plex algorithm in condensed tableau 
form. All slack, surplus and artificial 
variables required to solve a problem 
are inserted into the formulation au- 
tomatically. As in the algorithm in 
Listing 1, all arrays are dynamically 
dimensioned to accommodate the 
number of variables and the number 
of constraints and do not require user 
attention. 

The package sells for $29 on cas- 
sette ($33 on diskette) and includes a 
transportation algorithm (modified 
distribution method), and a network 
flow optimization algorithm (out-of- 
kilter method) in addition to the sim- 
plex algorithm. 

Conclusion 

Personal computers are devices 
with vast problem-solving capabili- 
ties. However, the literature on per- 
sonal computing suggests that these 
capabilities have been overlooked, 
while ofher capabilities such as ac- 
counting, word processing, education 
and games are touted. 

One such problem— the problem of 
maximizing profits— has been treated 
here. Once formulated, the problem 
is easily solved by the computer pro- 
gram in Listing 1. The solution to the 
problem informs the problem solver 
which product mix is best— that is, 
how much of each product (or ser- 
vice) to produce (or provide). In addi- 
tion, the solution tells the user to 
which resource the profit is most sen- 
sitive. This is the resource which, if 
increased, will cause the greatest in- 
crease in profit. ■ 



MAXIMUM OBJECTIVE FUNCTION VALUE IS 8.7 
MAXIMUM VALUE FOR VARIABLE 4 IS .35 
MAXIMUM VALUE FOR VARIABLE 8 IS .3 
MAXIMUM VALUE FOR VARIABLE 16 IS .35 
HIT ENTER TO SEE SHADOW PRICES-OK? 
SENSITIVITY COEFFICIENTS (DUAL VARIABLES) ARE 


8 
1 


1 
HIT ENTER TO END? 

Sample 2b. 



162 Microcomputing, August 1981 



Listing continued from page 80. 



0000 
0000 
0000 

cooo 
cooo 
cooo 
cooo 
cooo 

1030 

1030 

1030 

1030 

1030 

1030 

1030 

0030 

0030 

0007 

0007 

0007 

0007 

0007 

0007 

0007 

0007 

0007 

0007 

BFFO 

BFFO 

BFFO 

BFFO 

0000 

0000 

0001 

0001 

0002 

0002 

0003 

0003 

0004 

0004 

0005 

0005 

0006 

0006 

0007 

0007 

0008 

0008 

0009 

0009 

OOOA 

OOOA 

OOOB 

OOOB 

OOOC 

OOOC 

OOOD 

OOOD 

OOOD 

OOOD 

OOOD 

OOOD 

OOOD 

OOOD 

OOOD 

OOOD 

OOOD 

OOOD 

OOOD 

1030 

1030 

1032 

1034 

1036 

1037 

1038 

1039 

103B 

103B 

10 3F 

103F 

1042 

1044 

1047 

1048 

104B 

104D 

104F 

1051 

1053 

1056 

1058 

1058 

1058 



0000 

0000 

0000 

E5 

D5 

C5 

DDE 5 

DD21F0BF 

DD7E0D 

FEOO 

C27B10 

78 

DD7007 

D606 

382C 

FE0 8 

3805 

CD1611 

1823 



380 
390 
400 
410 
420 
430 
440 
450 
460 
470 
480 
490 
500 
510 
520 
530 
540 
550 
560 
570 
580 
590 
600 
610 
620 
630 
635 
640 
650 
660 
670 
672 
674 
680 
690 
700 
710 
720 
730 
740 
750 
760 
770 
780 
790 
800 
810 
820 
830 
840 
850 
860 
870 
880 
890 
900 
910 
920 
930 
960 
9 70 
999 
1000 
1005 
1010 
1020 
1030 
1040 
1050 
1060 
1070 
1072 
1074 
1076 
1080 
1090 
1100 
1105 
1106 
1110 
1120 
1122 
1124 
1126 
1130 
1140 
1150 
1160 
1170 
1180 
1190 
1200 
1210 
1220 
1230 



;VIDEO IS THE BEGINNING ADDRESS ASSIGNED TO THE 
; MEMORY MAPPED VIDEO RAM. ITS VALUE IS STORED 
; IN THE BUFFER AREA FOR EASY MODIFICATION. 
ORIG 0C000H 
: VIDEO ; 

• 
9 

;LOC IS THE BEGINNING ADDRESS OF THIS VIDEO 
; DRIVER ROUTINE SOFTWARE 
ORIG 1030H 
: LOC 

• 
| 

;RWMAX REPRESENTS THE MAXIMUM ROW COUNT FOR 

;THE VIDEO SCREEN. IT IS THE TOTAL CHARACTERS 

; COUNT UP TO THE FIRST SPOT ON THE LAST 

;ROW. FOR 24 LINES, THE COUNT IS 07 30H 

ORIG 30H 

: RWMAXL ; 

ORIG 7 

: RWMAXH ; 

I 

;15 BYTES OF RAM ARE NEEDED FOR HOUSEKEEPING. 

; THESE BYTES MUST BE IN AN AREA UNUSED BY 

; OTHER PROGRAMS. THE BASE ADDRESS IS STORED 

;IN REGISTER IX EACH TIME THE ROUTINE IS USED. 

; MERELY TWO ADDR CHANGES IN THIS PROGRAM WILL 

;RELOCATE THIS BUFFER AREA. THEY ARE LOCATED 

;IN STATEMENTS 1110 AND 5310. 

ORIG OBFFO 

: BUFFER ; 

• 
I 

; ASSIGN VALUES TO BUFFER POINTERS 
ORIG 
: SPARE ; 
ORIG 1 
:VIDLO 
ORIG 2 
:VIDHI 
ORIG 3 
:BUFLO 
ORIG 4 
:BUFHI 
ORIG 5 
:HOMLO 
ORIG 6 
:HOMHI 
ORIG 7 
tCHARTR 
ORIG 8 
:CURLO 
ORIG 9 
:CURHI 
ORIG OAH 
:ROWLO 
ORIG OBH 
:ROWHI 
ORIG OCH 
: COLUMN ; 
ORIG ODH 
PLOTTR ;NON-ZERO WHEN PLOTTING 



*************************** 

******* SECTION 1 ********* 
*************************** 

NORMAL ENTRY POINT 

EXPECTS CHARACTER OR COMMAND IN B 

RETURNS CHARACTER IN A 

PRINTS ALL BYTES LARGER THAN 0EH 



ORIG LOC 

FCDB 

FCDB 

FCDB 

PUSH HL ;SAVE HL ON STACK 

PUSH DE ;DE TOO 

PUSH BC ;BC TOO 

PUSH IX ;ALSO IX 

(MUST BE USER PERSONALIZED) 
LD IX, BUFFER INITIALIZE BUFFER AREA 

TAKES 16 BYTES OF RAM. 
LD A, (IX+PLOTTR) 
CP 

JP .NZ,EXIT ;DO NOT PRINT IF GRAPHICS MODE 
LD A,B ; CHARACTER TO A 
LD (IX+CHARTR) ,B ; STORE CHAR IN BUFFER 
SUB 6 ;EXIT IF CNTL-A TO CNTL-F 

JR .C,EXIT 

CP 8 ;TEST IF CHAR IS A VIDEO CMD 

JR .C,CMDVCT ;IF SO, VECTOR TO CMD 
CALL CHAROT 
JR EXIT 



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Microcomputing, August 1981 163 



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Listing 2 continued. 

1058 3D 

1059 E607 
105B CB07 
105D 216D10 

1060 1600 

1062 5F 

1063 19 

1064 5E 

1065 23 

1066 56 

1067 EB 

1068 117B10 
106B D5 
106C E9 
106D 
106D 
106D 
106D 
106D 
106F 
1071 
1071 
1073 
1075 
1075 
1077 
1079 
107B 
107B 
10 7B 
107B 
107D 
10 7E 
10 7F 
1080 
1081 
1082 
1082 
10 82 
1082 
1085 
1087 
1089 
10 8C 
108D 
1091 
1094 
1097 
109A 
109B 
109B 
109B 
109B 
109E 
10A0 
10A2 
10A5 
10A6 
10AA 
10 AD 
10B0 
10B3 
10B4 
10B4 
10B4 
10B4 
10B7 
10B8 
10B9 
10BB 
10BC 
10 BE 
10C1 
10C4 
10C5 

10C5 

10C5 

10C5 

10C5 CD6112 

10C8 3E30 

10CA BD 

10CB 2008 

10CD 3E07 

10CF BC 

10D0 2003 

10D2 CDB011 

10D5 CD6F11 

10D8 C9 

10D9 

10D9 

10D9 

10D9 DD360C00 

10DD 210000 

10E0 CD6812 

10E3 CDA111 

10E6 CD1A12 



0B11 
8210 

B410 
C510 

9B10 
D910 
EA10 



DDE1 

CI 

78 

Dl 

El 

C9 



DD7E0C 

FE00 

2804 

CD8011 

C9 

DD360C4F 

CD6112 

CDA111 

CD1A12 

C9 



DD7E0C 

FE4F 

3004 

CD5D11 

C9 

DD360C00 

CD6112 

CDA111 

CD1A12 

C9 



CD6112 

AF 

BD 

2006 

BC 

2003 

CDDA11 

CD8E11 

C9 



1240 

1250 

1260 

1270 

1280 

1290 

1300 

1310 

1320 

1330 

1340 

1350 

1360 

1370 

1380 

1390 

1400 

1405 

1410 

1420 

1430 

1440 

1450 

1460 

1470 

1480 

1490 

1500 

1510 

1520 

1530 

1532 

1535 

1540 

1550 

1560 

1600 

1610 

1620 

1630 

1640 

1650 

1660 

1670 

1680 

1690 

1700 

1710 

1720 

1740 

1750 

1760 

1770 

1780 

1790 

1800 

1805 

1810 

1820 

1830 

1840 

1850 

1860 

1870 

1880 

1890 

1900 

1910 

1920 

1930 

1940 

1950 

1960 

1970 

1980 

1990 

2000 

2010 

2020 

2030 

2040 

2050 

2060 

2070 

2080 

2090 

2100 

2110 

2120 

2130 

2140 

2150 

2160 

2170 

2180 

2190 



DEC A 
;MASK 



OFF UPPER 5 BITS 



; ZERO 
;MOVE 



: CMDVCT 

AND 07H 

RLC A 

LD HL, VECTOR 

LD D,0 

LD E,A 

ADD HL,DE 

LD E, (HL) 

INC HL 

LD D, (HL) ; UPPER BYTE OF VECTOR TO D 

EX DE,HL ; VECTOR TO HL 

LD DE,EXIT ;ADDR OF EXIT ROUTINE TO 

PUSH DE .-STORE ON STACK FOR 'RET' 



;BASE OF CMD VECTOR TABLE 

D 

OFFSET TO E 
;HL HOLDS VECTOR TABLE 
; LOWER BYTE OF VECTOR TO 



ADDR 
E 



DE 



JP (HL) 



TRANSFER PROG CNTL TO HL 



ADDR TABLE FOR VIDEOGRAPHIC COMMANDS 



VECTOR ; 
FCDB BELLS 
FCDB BACKSP 



FCDB 
FCDB 

FCDB 
FCDB 
FCDB 



LASTRW 
NEXTRW 

FWDSP 

HOME 

CRRTN 



;CNTL-G RING A BELL 
;CNTL-H BACKSPACE 

(CURSOR BACK) 
; CNTL- I CURSOR UP 
; CNTL- J LINEFEED 

(CURSOR DOWN) 
;CNTL-K CURSOR FORWARD 
;CNTL-L CURSOR HOME 
;CNTL-M CARRIAGE RETURN 



EXIT ROUTINE RESTORES REGISTERS 



EXIT POP 
POP BC 
LD A,B 
POP DE 
POP HL 
RET 



IX ; RESTORE IX 
;BC TOO 
; CHARACTER TO A 



RETURN TO USER'S PROGRAM 



CURSOR BACK ROUTINE 



LD 



A, (IX+COLUMN) 
;IS IT ZERO? 



;IF SO, JUMP 
; SHIFT CURSOR 



BACKSP 
CP 

JR .Z,BACK1 
CALL REG I 
RET 

: BACK 1 LD (I X+COLUMN ) , 4F H 
CALL HL)ROW ;SAVE 79D IN ROW CNT 
CALL CALCUR ; CALCULATE NEW CURSOR 
CALL CURSLD 
RET 



CURSOR FORW RD ROUTINE 



; COLUMN CNT TO A 



1 COLUMN LEFT 



;LAST LINE COLMN 



LD 



A, (IX+COLUMN) 

IS A LESS THAN 79D? 
JP IF END OF LINE 
ADVANCE CURSOR 



FWDSP 
CP 4FH 
JR .NC,FWD1 
CALL ADVI 
RET 

:FWD1 LD (IX+COLUMN) ,0 
CALL HL)ROW ;ROW CNT TO 
CALL CALCUR 
CALL CURSLD 
RET 



; ZERO 
HL 



COLUMN CNT 



CURSOR UP ROUTINE 



LASTRW 
XOR A 
CP L 

JR .NZ,LAST4 
CP H 

JR .NZ,LAST4 
CALL ROLLDN 
: LAST 4 CALL 
RET 



CALL HL)ROW 
;ZERO A 



ROW CNT TO HL 



IS L=0? 



IS H=0? 



; SINCE FIRST ROW, ROLL- DOWN 
REGIII ;MOVE CURSOR UP 1 ROW 



CURSOR DOWN ROUTINE 
DOES NOT CLEAR NEXT 



LINE IF ROLLED-UP 



NEXTRW CALL 
LD A,RWMAXL 
CP L 

JR .NZ,NEXT4 
LD A,RWMAXH 
CP H 

JR .NZ,NEXT4 
CALL ROLLUP 
: NEXT 4 CALL 
RET 



HL)ROW 
;0730H 



;ROW CNT TO HL 
IS ROW CNT FOR 
;THE LAST LINE 
;JP IF L#80H 
;NOW CHECK H 
;IS H=7? 



;IT IS 
ADVI I I 



THE LAST 
; ADVANCE 



LINE, SO 
CURSOR 1 



ROLL 
LINE 



CURSOR HOME ROUTINE 



ZERO COLUMN CNT 



HOME LD ( I X+COLUMN ) , 
LD HL,0 ;ZERO HL 

CALL ROW)HL ; ZERO ROW CNT 
CALL CALCUR ; CALCULATE CURSOR'S ADDR 
CALL CURSLD ;LOAD CURSOR AT 'HOME' 




164 Microcomputing, August 1981 



Listing 2 continued 

10E9 C9 

10EA 

10EA 

10EA 

10EA 

10EA 

10EA 

10ED 

10FO 

10F2 

10F3 

10F5 

10F7 

10F8 

10FA 

10FD 

1100 

1104 

1107 

110A 

HOB 

HOB 

HOB 

HOB 

HOD 

110F 

1111 

1113 

1115 

1116 

1116 

1116 

1116 

1119 

111B 

HID 

1120 

1123 

1124 

1127 

1129 

112B 

112E 

1130 

1132 

1135 

1138 

1139 

113C 

113F 

1142 

1145 

1146 

1146 

1146 

1146 

1149 

114C 

114D 

1150 

1151 

1154 

1157 

1158 

115B 

115C 

115D 

115D 

115D 

115D 

115D 

115D 

115D 

115D 

115D 

115D 

115D 

1160 

1163 

1164 

1167 

116A 

116B 

116B 

116B 

116B 

116B 

116B 

116B DD360C00 

116F 

116F 

116F 

116F 

116F 

116F 

116F CD6112 



CD1611 

CD6112 

3E30 

BD 

200B 

3E07 

BC 

2006 

CDB011 

CD0612 

DD360C00 

CDA111 

CD1A12 

C9 



DBOO 
E680 
28FA 
3E07 
D301 
C9 



DD7E0C 

FE4F 

2807 

CD4611 

CD5D11 

C9 

DD7E0B 

FE07 

2007 

DD7E0A 

FE30 

2807 

CD4611 

CD6B11 

C9 

CD4611 

CDB011 

CD0612 

CD6B11 

C9 



CD6112 

CDA111 

E5 

CDF611 

El 

CD7D12 

CD3E12 

19 

DD7E07 

77 

C9 



DD340C 

CD6F12 

23 

CD7612 

CD1A12 

C9 



2200 

2210 

2220 

2230 

2240 

2250 

2260 

2270 

2280 

2290 

2300 

2310 

2320 

2330 

2340 

2350 

2360 

2370 

2374 

2378 

2380 

2390 

2400 

2410 

2420 

2430 

2440 

2450 

2460 

2600 

2610 

2620 

2630 

2640 

2650 

2660 

2670 

2680 

2690 

2700 

2710 

2720 

2730 

2740 

2750 

2760 

2770 

2780 

2790 

2800 

2810 

2820 

2830 

2840 

2850 

2860 

2870 

2880 

2890 

2900 

2905 

2910 

2930 

2940 

2950 

2960 

3000 

3005 

3010 

3015 

3020 

3030 

3040 

3050 

3060 

3070 

3080 

3090 

3100 

3120 

3125 

3130 

3140 

3150 

3160 

3170 

3180 

3190 

3200 

3210 

3220 

3230 

3240 

3250 

3260 

3270 



RET 



CARRIAGE RETURN ROUTINE 

CLEARS THE NEXT LINE IF A ROLL- UP OCCURS 
DEPOSITS 'OD' IN MEMORY AS CR 



:CRRTN CALL CHAROT ;DEP CR IN MEMORY 

CALL HL)ROW ;ROW COUNT TO HL 

LD A,RWMAXL ;CHECK IF LAST LINE L=80H? 

CP L 

JR ,NZ,CRR2 

LD A,RWMAXH ;H>7? 

CP H 

JR .NZ,CRR2 

CALL ROLLUP jLAST LINE, SO ROLL-UP SCREEN 

CALL CLRLIN ;FILL NEXT LINE W/ SPACES 

:CRR2 LD (IX+COLUMN) ,0 ;PUT CURSOR BOL 

CALL CALCUR 

CALL CURSLD 

RET 



RING A BELL ROUTINE 



BELLS IN A, (00H) ;CHECK STATUS 



AND 80H 
JR .Z, BELLS 
LD A,07H 
OUT (01H) ,A 

RET 



;MASK OFF BYTE 

;JP BACK IF NOT READY 

;A HOLDS ASCII BELL 

;SET I/O ADDR FOR YOUR MACHINE 



CHARACTER POSITIONING ROUTINE 
CHAROT LD A, (IX+COLUMN) ; COLUMN CNT TO A 



;IS IT 79D? 

;JP IF LAST CHAR IN ROW 
;LOAD CHARACTER TO MEM 
; ADVANCE CURSOR 



CP 4FH 

JR . Z,CHAR2 

CALL CHARLD 

CALL ADVI 

RET 

:CHAR2 LD A, (IX+ROWHI) ;GET ROW CNT 

CP RWMAXH ; CHECK IF LAST ROW 

JR .NZ,CHAR4 ;JP IF NOT YET 

LD A, (IX+ROWLO) 

CP RWMAXL ;LOW BYTE MATCH? 

JR .Z,CHAR6 ;JP IF SO, LAST LINE 

:CHAR4 CALL CHARLD 

CALL ADVI I 

RET 

:CHAR6 CALL CHARLD ;LOAD CHAR IN LAST POSIT 

CALL ROLLUP ; SCROLL IN A NEW LINE 

CALL CLRLIN ; CLEAR NEW LINE 

CALL ADVI I ;MOVE CURSOR TO NEW LINE 

RET 

• 

; LOAD CHARACTER ROUTINE 

| 

: CHARLD CALL HL)ROW ;ROW CNT TO HL 
CALL CALCUR ; CALCULATE CURSOR ADDR 

;SAVE THAT ADDR 

; CLEAR ROW CHAR TEST ROUTINE 



PUSH HL 
CALL CLRROW 
POP HL 
CALL MASK8K 
CALL DE)VID 
ADD HL,DE 



;MASK END AROUND 

; MEMORY MAPPED VIDEO ADDR TO DE 
;HL NOW HOLDS ABSOLUTE ADDR 
LD A, (IX+CHARTR) ;CHAR BYTE TO A 
LD (HL) ,A ;LOAD BYTE TO MEMORY 
RET 

********************** 

**** SECTION 2 ******* 
********************** 

ELEMENTAL SUBROUTINES FOR VIDEO 



MIDDLE OF SCREEN CURSOR ADVANCE 
CURSOR AND COLUMN INCREMENT 

ADVI INC (IX+COLUMN) ; INCREMENT COLUMN CNT 
CALL HL)CUR ; CURSOR ADDR TO HL 
INC HL ; POINT TO NEXT CHAR 
CALL CUR)HL ; STORE HL TO CURSOR 
CALL CURSLD 
RET 



END OF LINE CURSOR ADVANCE 

CURSOR AND COLUMN TO NEXT LINE 
ROW COUNT INCREMENTS BY 1 
CONTINUES TO ADVI I I 

ADVI I LD (IX+COLUMN) ,0 ; ZERO COLUMN CNT 

MIDDLE OF LINE CURSOR DOWN 

CURSOR STAYS IN SAME COLUMN BUT 

ON THE NEXT LINE 
EXPECTS THAT NEXT LINE IS ON SCREEN 

ADVI I I CALL HL)ROW ;ROW CNT TO HL 



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Microcomputing, August 1981 165 




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Listing 2 continued. 




1172 115000 


3280 LD DE,50H ; 80D TO DE 


1175 19 


3290 ADD HL,DE ;HL=R0W CNT + 80D 


1176 CD6812 


3 300 CALL ROW)HL ; STORE NEW ROW CNT 


1179 CDA111 


3310 CALL CALCUR ; CALCULATE NEW CURSOR 


117C CD1A12 


3320 CALL CURSLD 


117F C9 


3330 RET 


1180 


3340 ; 




1180 


3350 ; 


MIDDLE OF SCREEN CURSOR REGRESS 


1180 


3360 ; 


CURSOR MOVES BACK 1 LOCATION 


1180 


3370 ; 


CURSOR AND COLUMN CNT DECREMENTED 


1180 


3380 ; 




1180 DD350C 


3390 : 


REG I DEC (IX+COLUMN) ; DECREMENT COLUMN CNT 


1183 CD6F12 


3400 CALL HL)CUR ; CURSOR LOC TO HL 


1186 2B 


3410 DEC HL 


1187 CD7612 


3 430 CALL CUR)HL ; SAVE NEW CURSOR 


118A CD1A12 


3440 CALL CURSLD 


118D C9 


3450 RET 


118E 


3460 ; 




118E 


3470 ; 


MIDDLE OF LINE CURSOR UP 


118E 


3480 ; 


CURSOR REMAINS IN SAME COLUMN BUT 


118E 


3490 ; 


ONE LINE HIGHER 


118E 


3500 ; 


EXPECTS HIGHER LINE TO BE ON SCREEN 


118E 


3510 ; 




118E CD6112 


3520 : 


REGIII CALL HL)ROW 


1191 115000 


3530 LD DE,50H ; 80D TO DE 


1194 B7 


3540 OR A ; CLEAR CARRY FLAG 


1195 ED52 


3550 SBC HL,DE ;HL=ROW COUNT - 80D 


1197 CD6812 


3560 CALL ROW)HL ;SAVE NEW ROW CNT 


119A CDA111 


3570 CALL CALCUR ; CALCULATE NEW CURSOR ADDR 


119D CD1A12 


3580 CALL CURSLD 


11A0 C9 


3590 RET 


11A1 


3600 j 




11A1 


3610 


f CALCULATE CURSOR ADDR ROUTINE 


11A1 


3620 


, USES HOME ADDR + COLUMN CNT 


11A1 


3630 


, + ROW CNT. EXPECTS ROW CNT IN HL 


11A1 


3640 




11A1 1600 


3650 


: CALCUR LD D,0 ; ZERO D 


11A3 DD5E0C 


3660 LD E, (IX+COLUMN) ;COLUMN CNT TO E 


11A6 19 


3670 ADD HL,DE ; HL=ROW+COLUMN 


11A7 EB 


3680 EX DE f HL ; SAVE IN DE 


11A8 CD5312 


3690 CALL HL)HOM ;HOME ADDR IN HL 


11AB 19 


3700 ADD HL,DE ; HL=ROW+COLUMN+HOME 


11AC CD7612 


3720 CALL CUR)HL ; STORE IN HL 


11AF C9 


3730 RET 


HBO 


3740 




HBO 


3750 


; ROLL-UP ROUTINE 


HBO 


3760 


; ROLLS SCREEN UP 1 LINE BASED ON HOME 


HBO 


3770 


| CURSOR AND COLUMN CNT STAY ON SAME CHAR 


HBO 


3780 


; DECREMENTS ROW CNT BY ONE 


HBO 


3790 


; DOES NOT CLEAR NEW LINE, 1ST CHAR ADDR 


HBO 


3800 


; ON THE NEW LINE IS IN IX+BUFF 


HBO 


3810 




HBO 115000 


3820 


:ROLLUP LD DE,50H ; 80D TO DE 


11B3 D5 


3830 PUSH DE ;SAVE IT 


11B4 CD5312 


3840 CALL HL)HOM ;HOME ADDR TO HL 


11B7 19 


3850 ADD HL,DE ;NEW HOME ADDR 


11B8 CD7D12 


3860 CALL MASK8K ; ADJUST FOR END- AROUND 


11BB CD5A12 


3870 CALL HOM)HL ;SAVE HOME 


11BE 1607 


3880 LD D,RWMAXH ;LAST ROW HIBYTE TO D 


11C0 1E30 


3 890 LD E,RWMAXL ;LAST ROW LOBYTE TO E 


11C2 19 


3900 ADD HL,DE ;HL=1ST CHAR IN NEXT LINE 


11C3 CD7D12 


3910 CALL MASK8K ;MASK END AROUND 


11C6 CD4C12 


3920 CALL BUF)HL 


11C9 B7 


3930 OR A ; CLEAR CARRY 


11CA Dl 


3940 POP DE ;80D TO DE 


11CB CD6112 


3950 CALL HL) ROW ; ROW CNT TO HL 


11CE ED52 


3960 SBC HL,DE ;HL=ROW CNT - 80D 


11D0 CD7D12 


3970 CALL MASK8K 


11D3 CD6812 


3980 CALL ROW) HL ; SAVE NEW ROW CNT 


11D6 CD2C12 


3990 CALL HOMLD ;READDJUST VIDEO HOME ADDR 


11D9 C9 


4000 RET 


11DA 


4010 




11DA 


4020 


; ROLL-DOWN ROUTINE 


11DA 


4030 


ROLLS SCREEN DOWN 1 LINE 


11DA 


4040 


INCREMENTS ROW COUNT BY ONE LINE 


11DA 


4050 


; CURSOR AND COLUMN STAY AT SAME CHAR 


11DA 


4060 


1 


11DA 115000 


4070 


:ROLLDN LD DE,50H ; 80D TO DE 


HDD D5 


4080 PUSH DE V 


11DE CD5312 


409 CALL HL)HOM ;HOME ADDR TO HL 


11E1 B7 


4100 OR A ; CLEAR CARRY FLAG 


11E2 ED52 


4110 SBC HL,DE ;HL=NEW HOME ADDR 


11E4 CD7D12 


4120 CALL MASK8K 


11E7 CD5A12 


4130 CALL HOM)HL ;SAVE HOME 


11EA CD6112 


4140 CALL HL)ROW ;ROW CNT TO HL 


11ED Dl 


4150 POP DE ;80D IN DE 


11EE 19 


4160 ADD HL,DE 


11EF CD6812 


4170 CALL ROW)HL ;SAVE NEW ROW CNT 


11F2 CD2C12 


4180 CALL HOMLD ; READJUST VIDEO HOME ADDR 


11F5 C9 


4190 RET 


11F6 


4200 ; 


11F6 


4210 ; CLEAR ROW TEST ROUTINE 


11F6 


4220 ; FILLS LINE W/ SP ■ S IF FIRST CHAR 


11F6 


4230 ; OF PRESENT LINE IS F0H 


11F6 


4240 ; -^ 


11F6 CD4512 


4250 


:CLRROW CALL HL) BUFF ;LOC OF 1ST CHAR (More v 



166 Microcomputing, August 1981 



Listing 2 continued. 



11F9 

11FC 

11FE 

11FF 

1200 

1201 

1204 

1205 

1205 

1205 

1205 

1205 

1206 

1209 

120C 

120D 

1210 

1213 

1214 

1216 

1217 

1218 

12 1A 

12 1A 

121A 

12 1A 

121C 

121E 

1221 

1222 

1224 

1226 

1228 

1229 

122B 

122C 

122C 

122C 

122C 

12 2E 

1230 

1233 

1234 

1236 

1238 

123A 

123B 

123D 

123E 

123E 

123E 

12 3E 

1241 

1244 

1245 

1248 

124B 

124C 

124F 

1252 

1253 



CD3E12 

3EF0 

19 

BE 

CO 

CD0612 

C9 



20 

CD4512 

CD3E12 

19 

015000 

110512 

EB 

EDAO 

EO 

2B 

18FA 



3E0F 

D370 

CD6F12 

7D 

D371 

3E0E 

D370 

7C 

D371 

C9 



3E0D 

D370 

CD5312 

7D 

D371 

3E0C 

D370 

7C 

D371 

C9 



DD5E01 

DD5602 

C9 

DD6E03 

DD6604 

C9 

DD7503 

DD7404 

C9 

DD6E05 
1256 1D6606 
1259 C9 

DD7505 

DD7406 

C9 

DD6E0A 

DD660B 

C9 

DD750A 

DD740B 

C9 

DD6E08 

DD6609 

C9 

DD7508 

DD7409 

C9 



125A 

125D 

1260 

1261 

1264 

1267 

1268 

126B 

126E 

126F 

1272 

1275 

1276 

1279 

12 7C 

127D 

127D 

12 7D 

127D 

12 7D 

12 7D 

127D 

12 7D 

127D 

127E 

127F 

1281 

1282 

1283 

1284 

1284 

1284 

1284 



F5 

7C 

E61F 

67 

Fl 

C9 



4270 

4280 

4290 

4300 

4310 

4320 

4330 

4340 

4350 

4360 

4370 

4380 

4390 

4400 

4410 

4420 

4430 

4440 

4450 

4460 

4470 

4480 

4490 

4500 

4510 

4520 

4530 

4540 

4550 

4560 

4570 

4580 

4590 

4600 

4610 

4620 

4630 

4640 

4650 

4660 

4670 

4680 

4690 

4700 

4710 

4720 

4730 

4740 

4750 

4760 

4770 

4780 

4790 

4800 

4810 

4820 

4830 

4840 

4850 

4860 

4870 



CALL DE)VID 
LD A,OFOH 
ADD HL,DE 
CP (HL) 
RET .NZ 
CALL CLRLIN 
RET 



; MEMORY MAP ADDR TO DE 
;CLEAR ROW DELIMITER 

;IS CHAR A OF OH? 
; RETURN IF NOT 
;FILL ROW W/ SPACES 



CLEAR LINE ROUTINE 

EXPECTS IX+BUFF TO HOLD 1ST CHAR OF LINE 

SPACE FCB 20H ; SPACE BYTE 

CLRLIN CALL HL) BUFF ;LOC OF FIRST CHAR 



CALL DE)VID 
ADD HL,DE 
LD BC,50H 
LD DE, SPACE 
EX DE,HL 
:CLR1 LDI 
RET .PC 
DEC HL 
JR CLR1 



ABSOLUTE MEM-MAPPED ADDR TO DE 

ABSOLUTE CHARACTER ADDR TO HL 

COUNTER BC HOLDS 80D 

DE POINTS TO 20H 

SWITCH DE + HL 

MOVE A SP TO MEMORY 
;EXIT WHEN BC=0 
;KEEP HL POINTING AT 20H 
; REPEAT TILL DONE 



LOADS CURSOR ADDR TO 6845 CHIP 



CURSLD LD 
OUT (70H) ,A 
CALL HL)CUR 
LD A,L 
OUT (71H) ,A 
LD A,0EH 
OUT (70H) ,A 
LD A,H 
OUT (71H),A 
RET 



A,0FH ;CURSOR LOW REGISTER 
; OUTPUT REG # TO 6 845 
; CURSOR ADDR TO HL 

; OUTPUT LO BYTE 

;REG # TO 6845 

; OUTPUT HI BYTE 



LOADS HOME ADDR TO 68 45 CHIP 



HOMLD LD A,0DH 
OUT (70H) ,A 
CALL HL)HOM 
LD A,L 
OUT (71H) ,A 
LD A,0CH 
OUT (70H) ,A 
LD A,H 
OUT (71H),A 
RET 



;REG # TO 6845 
;HOME ADDR TO HL 

; OUTPUT LO BYTE 



; OUTPUT HI BYTE 



ASSORTED LOADING ROUTINES 



:DE)VID LD E,(IX+VIDLO) 
LD D, (IX+VIDHI) 
RET 

:HL)BUF LD L, (IX+BUFLO) 
LD H, (IX+BUFHI) 
RET 

:BUF)HL LD (IX+BUFLO) ,L 
LD (IX+BUFHI) # H 
RET 

:HL)HOM LD L, (IX+HOMLO) 
4880 LD H,(IX+HOMHI) 
4 890 RET 

:HOM)HL LD (IX+HOMLO) ,L 

LD ( IX+HOMHI ) , H 

RET 

: HL ) ROW LD L , ( I X+ROWLO ) 

LD H, (IX+ROWHI) 

RET 

: ROW) HL LD ( IX+ROWLO) , L 

LD (IX+ROWHI) ,H 

RET 

:HL)CUR LD L, (IX+CURLO) 

LD H, (IX+CURHI) 

RET 

:CUR)HL LD (IX+CURLO) ,L 

LD (IX+CURHI) ,H 

RET 



4900 

4910 

4920 

4930 

4940 

4950 

4960 

4970 

4980 

4990 

5000 

5010 

5020 

5030 

5040 

5050 

5055 

5060 

5070 

5080 

5085 

5088 

5090 

5100 

5110 

5120 

5130 

5140 

5150 

5160 

5165 

5170 

5175 



MASK8K 

MASK OFF 3 

OF ADDR TO 

THE MEMORY 

NOTE: THE 

IT IS AN 



MOST SIGNIGICANT BITS 

SET END- AROUND ON VIDEO MAP. 

MAPPED SIZE 8K. 

CURSOR IS NOT MASKED SINCE 
INTERNAL COUNTER. 



MASK8K PUSH AF 
LD A,H 
AND 1FH 
LD H,A 
POP AF 
RET 
I 

.**** SECTION 3 ******* 



9 TRACK TAPE DRIVES 



800 BPI 

45 IPS 

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$2400 

NEW IN 

ORIGINAL 

BOXES 



PERTEC Model 8840A-9-45 

INDUSTRY STANDARD INTERFACE 

CAPABLE OF IND. STD. ANSI-IBM DATA FORMAT 

• READ WRITE DATA IN STANDARD ANSI-IBM COMPATIBLE 
FORMAT 

• DUMP WINCHESTERS AND HARD DISKS; 10 inch reels hold up to 
3600 of tape 34.56 Megabytes unblocked. 

• EXCHANGE DATA A PROGRAMS WITH LARGE MAIN FRAMES 
AT SCHOOL. WORK. SERVICE BUREAUS ETC 

• BARGAIN PRICED MINI-COMPUTER UPGRADE OEM List S48S0 

A large OEM overstock makes these industry standard drives available at 
a traction ot their current list price Full size drives handle up to 10 5 inch 
reels of standard inexpensive 1/2 inch mag tape 19 inch rack mount or 
use right out of the box on steel shipping frame 

SPECIFICATION SUMMARY: 9-track. 800 BPI. dual head (read after 
write). 45 IPS read/write. 200 IPS rewind, BOT/EOT sensing, 110 
VAC/60-Hz. solid state, recent manufacture, all I/O signals TTL/DTL 
compatible, tension arm tape buffering, full control panel Call or write for 
full set of technical specifications 

INTERFACES: Electrovalue encourages the development of interfaces to 
popular systems Interfaces exist for popular minis and are being 
developed for several hobby computers If you'd like to develop and 
document an interface to a popular small system call to discuss 
discounts. 



ELECTROVALUE INDUSTRIAL INC. 

PO. BOX 157-K f-j 

MORRIS PLAINS. NJ 07950 C sdl 

Formerly ElKlrmluc Industrial ''•\ 




Phone reservations and 
questions are welcome 

201/267-1117 



BUY! SELL! TRADE! 

COMPUTER & HAM EQUIPMENT 

\Z COMPUTER 
T TRADER .. 176 

GREEN SHEETS" 

Mailed 1st class, 1st and 15th of every month 

SEND ADS FIVE DAYS BEFORE MAILING DATE 
— RATES — 
Subscriptions Ads 

One Year $10 00 Hobby 20 c Word/Number 

Six Months $6 00 Business 55 c Word/Number 

Per Copy $100 (Non-Subscriber Add15 c 

Word/Number) 
SAVE 50% on your 1st ad accompanying your subscription 
Send Ads and Subscriptions with remittance to: 

COMPUTER TRADER® 

Chet Lambert, W4WDR 

1704 Sam Drive • Birmingham, AL 35235 

(205) 854-0271 
For ads count name and address, words and numbers 
(zip/area code free) 

Please include your name, address, call sign or phone number 




^\#y^ y ° u * ve written 

(CvgT a Fan t as tic Game ? 

^* Then We'd Like to Publish It! 

We're looking for hot GAME pro- 
grams: 

ARCADE (HI-SPEED GRAPHICS) 

ADVENTURE FORMAT 

FANTASY WARGAMING 

BOARD GAMES 

LOGIC & PUZZLE GAMES 

There's Gold in them there 
Games! Write for our free 
Programmer's Kit today. 

INSTANT SOFTWARE, INC. ^75 
Submissions Dept. 
Peterborough, NH 03458 



^See List of Advertisers on page 194 



Microcomputing, August 1981 167 



^ SOFTWARE FOR OSI 

K-, VIDEO GAMES 3 NE^I $14.95 

y^ Three games Meteor Mission is an asteroids game 
Space Wars is a battle between two starships Meteor 
■<t Wars is a combination of the two above games All three 
' are in machine language with fast, real time action, and 

K* super graphics KJp W- 

»* ADVENTURE: IMMORTALITY * $11.95 

k^ You are an intrepid explorer searching for the fabled 
)A Dust of Immortality" This is the largest adventure yet 
available for 8K OSM hidden room load so you can't cheat 

V SUPER BUG! $6.95 

Heres a super-fast. BASIC/Machine language hybird 
■^J race game Ten levels of difficulty and a infmately 
" changing track will keep you challenged 

*& STARGATE MERCHANT $9.95 

You are a trader in the distant future, traveling through 
£f stargates to get to various star systems Part video 
r* game part board game, always challenging 

>r DISASSEMBLER $11.95 

•^ Use this to look at the ROMs in your machine tosee what 

/j^ makes BASIC tick Reconstruct the assembler source 
^l code of machine language programs to understand how 
they work Our disassembler outputs unique suffixes 
which identify the addressing mode being used, no other 
proqram has this' 
^ MAROONED IN SPACE $11.95 

k An adventure that runs in 8K 1 Save your 

ik ship and yourself from destruction 

I SUPER! BIORHYTHMS $14.95 
' A unique sophisticated biorhythm program 

DUNGEON CHASE $9.95 

"j real-time video game where you explore a dungeon 

^/ . ^^ ^^ I ^^ |v | Write for FREE catalog 

^mW hi IKJ IN SOFTWARE ^329 
^147 Main St. Ossining. NY 10562 



IS YOUR 
°North Star 

OUT OF SORTS? 



INCREASE YOUR BASICS 
SORTING POWER OVER 1800%! 

N*S0RT is easy to use and will perform 
sorts on one and two dimensional or 
string arrays using optional sort keys. 
For example, to alphabetize A$: 

10 A$ - ZYXWVUTS'X REM Define String 
20 SRT A$.LEN(A$),1\ REM Sort AS 

N*S0RT interfaces to any release 4 or 

later North Star Basic and can be yours 

for only (tQQ . m 

\J)Ov7 plus $1.50 shipping 

Cahf. Res add 6% tax 
Send check VISA or M/C 
Complete Brochure Available 





% 



Software Systems 



1269 Rubio Vista Road. Altadena. Calif. 91001 

(213) 791-3202 A^~ 




2&F 

x\j& V You ' ve Written 

(^y State-of-the-Art Software- 

We'd Like to Publish It! 

We're looking for SYSTEM software: 

DISK OPERATING SYSTEMS 

MONITORS 

PROGRAMMER AIDS/UTILITIES 

LANGUAGES 

DATA BASE SYSTEMS 

Then, sit back and collect your 

royalty checks. Write for our free 

Programmer's Kit today! 

INSTANT SOFTWARE, INC. " 75 
Submissions Dept. 
Peterborough, NH 03458 



Listing 


2 continued. 






1284 




5180 j 


INITIALIZATION SECTION 


1284 




5182 ; 




1284 




5183 ; 


***CALL GRAPH AND INITIALIZE FOR GRAPHIC MODE 


1284 


21A112 


5184 : 


GRAPH LD HL, CLRMEM- 1 ; POINT TO 0FFH 


1287 


CDA212 


5186 CALL CLRMEM 


12 8A 


CDB012 


5187 CALL INITBF 


12 8D 


CD2813 


5188 CALL DOTS 


1290 


DD340D 


5189 INC (IX+PLOTTR) ;MAKE GRAPHICS FLAG NON-ZERO 


1293 


C9 


5190 RET 


1294 




5191 ; 


***CALL LTTRS AND INITIALIZE FOR CHARACTER MODE 


1294 


210512 


5192 : 


LTTRS LD HL, SPACE 


1297 


CDA212 


5193 CALL CLRMEM 


129A 


CDB012 


5194 CALL INITBF 
5196 CALL CHARS 


129D 


CDD912 


12A0 


C9 


5198 RET 


12A1 




5199 j 




12A1 




5200 ; 


FILL VIDEO MEMORY WITH SPACE OR FF ' S 


12A1 




5202 j 


HL MUST POINT TO CHARACTER TO BLANK SCREEN 


12A1 




5205 ; 




12A1 


FF 


520 8 FCB 0FFH 


12A2 


1100C0 


5210 : 


CLRMEM LD DE,0C000H ; FIRST ADDR OF 8K BOARD 


12A5 


010020 


5220 LD BC,2000H ; LENGTH OF MEMORY 


12A8 


EDA0 


5240 J 


CLRMM1 LDI ;MOVE A SPACE TO VIDEO 


12AA 


E0 


5250 RET .PO ;RET WHEN BC=0 


12AB 


2B 


5260 DEC HL ; CONTINUE TO POINT TO FILL CHAR 


12 AC 


18FA 


5270 JR CLRMM1 ; REPEAT 


12AE 


0000 


5274 FCDB 


12B0 




5280 j 


i 


12B0 




5290 j 


INITIALIZE VIDEOGRAPHIC BUFFER VALUES 


12B0 




5300 : 


• 


12B0 


DD21F0BF 


5310 : 


INITBF LD IX, BUFFER ;SET UP IX POINTER 


12B4 




5320 j 


NOTE: CHANGE VALUE OF BUFFER FOR 


12B4 




5330 i 


A DIFFERENT BUFFER LOCATION 


12B4 


210000 


5340 LD HL,0 ; ZERO HL 


12B7 


CD6812 


5350 CALL ROW)HL 


12BA 


CD4C12 


5360 CALL BUF)HL 


12BD 


CD7612 


5370 CALL CUR) HL 


12C0 (D5A12 


5380 CALL HOM)HL 


12C3 


DD360C00 


5390 LD (IX+COLUMN) ,0 ; ZERO COLUMN CNT 


12C7 


DD360D00 


5395 LD (IX+PLOTTR) ,0 ;RESET GRAPHICS FLAG 


12CB 


2100C0 


5400 LD HL, VIDEO 


12CE 


DD7501 


5410 LD (IX+VIDLO),L 


12D1 


DD7402 


5420 LD (IX+VIDHI),H 


12D4 


DD360D00 


5425 LD (IX+PLOTTR) ,0 ;RESET GRAPHICS FLAG FOR CHAR MODE 


12D8 


C9 


5430 RET 


12D9 




5500 




12D9 




5510 


1 INITIALIZE THE 6 845 CHIP FOR 24X80 DISPLAY 


12D9 




5520 




12D9 


0E00 


5530 


: CHARS LD C,0 


12DB 


0666 


5540 LD B,66H ;R0 H-TOTAL 


12DD 


CD2013 


5550 CALL CHIP 


12E0 


0650 


5560 LD B,50H ;R1 H-DISPLAYED 


12E2 


CD2013 


5570 CALL CHIP 


12E5 


0656 


5580 LD B,56H ;R2 H-SYNC 


12E7 


CD2013 


5590 CALL CHIP 


12EA 


060C 


5600 ] 


LD B,0CH ;R3 H- PULSE WIDTH 


12EC 


CD2013 


5610 CALL CHIP 


12EF 


0618 


5620 ] 


LD B,18H ;R4 V-TOTAL 


12F1 


CD2013 


5630 < 


:all CHIP 


12F4 


0613 


5640 ] 


LD B,13H ;R5 V- ADJUST 


12F6 


CD2013 


5650 l 


:all CHIP 


12F9 


0618 


5660 ] 


LD B,18H ;R6 V-DISPLAYED I 


12FB 


CD2013 


5670 CALL CHIP 


12FE 


0618 


5680 ] 


LD B,18H ;R7 V-SYNC 


1300 


CD2013 


5690 ( 


call CHIP 


1303 


0600 


5700 : 


LD B,0 ;R8 VIDEO MODE 


1305 


CD2013 


5710 1 


CALL CHIP 


1308 


060B 


5720 : 


LD B,0BH ;R9 SCANS/ROW 


130A 


CD2013 


5730 1 


CALL CHIP 


130D 


0649 


5740 


LD B,49H ;R10 CURSOR LIMIT HI 


130F 


CD2013 


5750 l 


C ALL CHIP 


1312 


060B 


5760 


LD B,0BH ;R11 CURSOR LIMIT LO 


1314 


CD2013 


5770 


CALL CHIP 


1317 


CD2C12 


5780 


CALL HOMLD ;R12 + R13 HOME ADDR 


131A 


CD1A12 


5790 1 


CALL CURSLD ;R14 + R15 CURSOR ADDR 


131D 


D361 


5800 


OUT (61H) ,A ;PUT VIDEO BOARD IN CHAR MODE 


131F 


C9 


5810 


RET 


1320 




5820 


• 
1 


1320 


79 


5830 


:CHIP LD A,C ;LOAD REGISTER CNT TO A 


1321 


D370 


5840 


OUT (70H),A ;SEND REGISTER ADDR TO 6845 


1323 


OC 


5850 


INC C 


1324 


78 


5860 


LD A,B 


1325 


D371 


5870 


OUT (71H) ,A ;SEND PROGRAMMING INFO TO 6845 


1327 


C9 


5880 


RET 


1328 




5890 


• 
1 


1328 




5900 


; INITIALIZE THE 6845 FOR 256X24 8 DISPLAY 


1328 




5910 


• 
1 


1328 


D360 


5920 


:DOTS OUT (6 OH) ,A ;PUT VIDEO IN GRAPHIC MODE 


132A 


213A13 


5930 


LD HL,DOTS2 


132D 


0E00 


5940 


LD C,0 


132F 


7E 


5950 


iDOTSl LD A, (HL) 


1330 


FEEE 


5960 


CP 0EEH 


1332 


C8 


5970 


RET . Z 


1333 


47 


5980 


LD B,A 


1334 


CD2013 


5990 


CALL CHIP 


1337 


23 


6000 


INC HL f *\ 


1338 


18F5 


6010 


JR DOTS1 (More ^ 



168 Microcomputing, August 1981 



* * * * * ******************* *** **** ********************* 

4MHZ, DOUBLE DENSITY,COLOR&B/W 
GRAPHICS . .THE LNW80 COMPUTER 



COMPARE THE FEATURES AND PERFORMANCE 




When you've compared the features of an LNW80 Computer, you'll quickly 
understand why the LNW80 is the ultimate TRS80 software compatible system. 
LNW RESEARCH offers the most complete microcomputer system at an outstand- 
ing low price. 

We back up our product with an unconventional 6 month warranty and a 10 
days full refund policy, less shipping charges. 

LNW80 Computer $1,450.00 

LNW80 Computer w/BSW Monitor & one 5" Drive $1,914.00 

All orders must be prepaid, CA residents please include 6% sales tax. 
Contact us for shipping charges 



* TRS80 
** PMC 



Product of Tandy Corporation. 

Product of Personal Microcomputer, Inc, 



FEATURES 




LNW80 


PMC- 80** 


TRS-80* 
MODEL III 


PROCESSOR 




4.0 MHZ 


1 ,8 MHZ 


2.0 MHZ 


LEVEL II BASIC INTERP. 

TRS80 MODEL 1 LEVEL II COMPATIBLE 


YES 

YES 


YES 
YES 


LEVEL III 
BASIC 

NO 


48K BYTES RAM 




YES 


YES 


YES 


CASSETTE BAUD RATE 




500/1000 


500 


500/1500 


FLOPPY DISK CONTROLLER 




SINGLE/ 
DOUBLE 


SINGLE 


SINGLE/ 
DOUBLE 


SERIAL RS232 PORT 




YES 


YES 


YES 


PRINTER PORT 




YES 


YES 


YES 


REAL TIME CLOCK 




YES 


YES 


YES 


.'4 X 80 CHARACTERS 




YES 


NO 


NO 


\HDE0 MONITOR 




YES 


YES 


YES 


UPPER AND LOWER CASE 




YES 


OPTIONAL 


YES 


REVERSE VIDEO 




YES 


NO 


NO 


KEYBOARD 




63 KEY 


53 KEY 


53 KEY 


NUMERIC KEY PAD 




YES 


NO 


YES 


B/W GRAPHICS, 128 X 48 




YES 


YES 


YES 


HI -RESOLUTION B/W GRAPHICS, 


480 X 192 


YES 


NO 


NO 


HI-RESOLUTION COLOR GRAPHICS 
128 X 192 IN 8 COLORS 


(NTSC), 


YES 


NO 


NO 


HI-RESOLUTION COLOR GRAPHICS 
384 X 192 IN 8 COLORS 


(RGB), 


OPTIONAL 


NO 


NO 


WARRANTY 




6 MONTHS 


90 DAYS 


90 DAYS 


TOTAL SYSTEM PRICE 




$1 ,914.00 


$1,840.00 


$2,187.00 


LESS MONITOR AND DISK DRIVE 




$1 ,450.00 


$1,375.00 






LNW80 

- BARE PRINTED CIRCUIT BOARD & MANUAL $89.95 

The LNW80 - A high-speed color computer totally compatible with 
the TRS-80*. The LNW80 gives you the edge in satisfying your 
computation needs in business, scientific and personal computa- 
tion. With performance of 4 MHz, Z80A CPU, you'll achieve per- 
formance of over twice the processing speed of a TRS-80*. This 
means you'll get the performance that is comparable to the most 
expensive microcomputer with the compatibility to the world's 
most popular computer (TRS-80*) resulting in the widest soft- 
ware base. 



FEATURES: 



TRS-80 Model 1 Level II Software Compatible 

High Resolution Graphics 

. RGB Output - 384 x 192 in 8 Colors 

. NTSC Video or RF MOD - 128 x 192 in 8 Colors 

. Black and White - 480 x 192 

4 MHz CPU 

500/1000 Baud Cassette 

Upper and Lower Case 

16K Bytes RAM, 12K Bytes ROM 

Solder Masked and Silkscreened 



LNW SYSTEM EXPANSION 

BARE PRINTED CIRCUIT BOARD 

AND MANUAL $69.95 

WITH GOLD CONNECTORS $84.95 

The System Expansion will allow you to expand your LNW80, TRS-80*, 
or PMC- 80** to a complete computer system that is still totally 
software compatible with the TRS-80* Model 1 Level II. 



FEATURES: 



IVk Bytes Memory 

5" Floppy Controller 

Serial RS232 20ma I/O 

Parallel Printer 

Real Time Clock 

Screen Printer Bus 

On Board Power Supply 

Solder Masked and Silkscreened 



LNW RESEARCH 

CORPORATION 

2620 WALNUT 
TUSTIN CA. 92680 



»x198 



LNDoubler&DOS PLUS 3.3D 

Assembled and Tested W/DOS PLUS 3. 3D $175.00 

Double-density disk storage for the LNW Research's "System Expan- 
sion" or the Tandy's "Expansion Interface". The LNDoubler™ is 
totally software compatible with any double density software 
generated for the Percom's Doubler***. The LNDoublerTM provides 
the following outstanding features. 

. Store up to 350K bytes on a single 5" disk 

. Single and double density data separation 

. Precision write precompensation circuit 

. Software switch between single and double density 

. Easy plug in installation requiring no etch cuts, jumpers 

or soldering 

. 35, 40, 77, 80 track 5" disk operation 

. 120 day parts and labor Warranty 

*** Doubler is a product of Percom Data Company, Inc. 

DOS PLUS 3. 3D 

Micro Systems software's double density disk operating system. 
This operating system contains all the outstanding features of 
a well developed DOS, with ease in useability. 

KEYBOARD 

LNW80 KEYBOARD KIT $84.95 

The Keyboard Kit contains a 63 key plus a 10 key, P.C. board, and 
remaining components. 

CASE 



LNW80 CASE $84.95 

The streamline design of this metal case will house the LNU80, 
LWN System Expansion, LNW80 Keyboard, power supply and fan, 
LNDoublerTM, or LNW Data Separator. This kit includes all the 
hardware to mount all of the above. Add $12.00 for shipping 

PARTS AVAILABLE FROM LNW RESERARCH 
. 4116 - 200ns RAM 

6 chip set $26.00 

8 chip set $33.50 

16 chip set $64.00 

24 chip set $94.00 

32 chip set $124.00 

. LNW80 "Start up parts set" LNW80-1 $82.00 

. LNW80 "Video parts set" LNW80-2 $31.00 

. LNW80 Transformer LNW80-3 $18.00 

. LNW80 Keyboard cable LNW80-4 $16.00 

. 40 Pin computer to expansion cable $15.00 

. System Expansion Transformer $19.00 

. Floppy Controller (FD1771) and UART (TR1602) . . . $30.00 



ORDERS & I N FO. NO. 714 - 544 - 5744 
SERVICE NO 714-641-8850 



VISA MASTER CHARGE 
ACCEPTED 



UNLESS NOTED 

ADD $3 FOR SHIPPING 



**See List of Advertisers on page 194 



Microcomputing, August 1981 169 



ANALOG mm DIGITAL 
DIGIT f\Lmm ANALOG 

CONVERSION MODULES 

SOFTWARE 
CAIN CONTROL 



custom board test S 100 

mixobic high one 4 low inputs 



from 1 to 1024 



omplificr 
onwersion time 

12 bit 
channel differential 
high accurocu 



16 channel 
programmable gain instrumentation 

2 to 15 khz 



sample ond hold amplifier 
analog to digital 

S 100 



for additional details about the AD 100 4 and other 
fine California Data Corporation I00°c individually 
tested, high reliability products, circle the reader 
service card number below or for faster response 
write or call us 

CALIFORNIA DATA 

CORPORATION 

3475 Old Conejo Road. Suite C 10 
Newbury Park. CA 91320 

(805) 498-3651 



^299 



Single Board Microcomputer 





*■■ Hbfe 


m 


n 




m i 


■ 

■ 


K MM 


: i 


(0 




1 


-< 


• |MHMM| MB 
■f W: SBB V-i 


II 





SIhHHP wmmhM npai 




c 






1 


"mmmKm&Kmm 




r 




For The SS-50 or S-1DO Bus 


ONBOARD FEATURES 




• 6809 of 6807 Microprooauor 


STD 


n 
> 


• 24K byte* of E PROM RAM .pace 


STD 


• Serial RS-232 porl with 14 baud ratal 


STD 


a 16 Decoded Addreu Line* 


STD 


r 


a Jumper configurable Addrau Map 


STD 




a Floppy Disc Controller tor ttiraa 5" Drive* 


Option 


n 


a Printar port. Cantromc typa compatible 


Option 


a Kayboard/Parallal intartaoa 


Option 


z 


a Rum Fran DOS 


STD 


a QBUG Raudant Debug Monitor 


STO 





a IK by tat of RAM and 2K by tat of EPROM 


STD 




a DEALER/OEM INQUIRIES INVITED 




n 


a Check or Money Order 




m 


• P.ic. OCB 9 6803 aMK STD Inlurn t 19600 




OCB 9 6809 witn STO Itiwn 225 00 






Floppy Conliolki Option 76 00 
PrinWi /Keyboard Option 30 00 






CALL (306)974 0967 






LOGICAL DEVICES. INC ^ 373 

'It w Oakland Park Bl.d 
N Lauderdato. Pav 33311 


QE20Q2Q 1 












Kilobaud Microcomputing does not 
keep subscription records on the 
premises, therefore calling us only 
adds time and doesn't solve the prob- 
lem. 

Please send a description of the 
problem and your most recent ad- 
dress label to: 

Kilobaud Microcomputing 
Subscription Dept. 
PO Box 997 
Farmingdale, NY 11737 



Thank you and enjoy your subscription. 



Listing 2 continued. 






13 3A 




6020 ; 




133A 




6030 : 


DOTS2 j 6845 PARAMETERS FOR GRAPHICS 


133A 


6640 


6040 FCDB 4066H 7RO/RI 


13 3C 


4E09 


6050 FCDB 094EH ;R2/R3 


133E 


7F19 


6060 FCDB 197FH ;R4/R5 


1340 


7F7D 


6070 FCDB 7D7FH ;R6/R7 


1342 


0001 


6080 FCDB 010 OH ;R8/R9 


1344 


0000 


6090 FCDB ;RA/RB 


1346 


0000 


6100 FCDB ;RC/RD 


1348 


0000 


6110 FCDB ;RE/RF 


134A 


EE 


6120 FCB 0EEH ;END OF FILM 


134B 




7000 ; 




134B 




7005 ; 


********************* 


134B 




7010 ; 


**** SECTION 4 ******* 


134B 




7015 ; 


********************** 


134B 




7020 ; 




134B 




7030 ; 


SHORT GRAPHICS ROUTINES 


134B 




7040 ; 




134B 




7050 ; 


(SEE LINE 5184 TO INITIALIZE FOR GRAPHICS MODE) 


134B 




7055 ; 




134B 




7060 ; 


THE GRAPHICS IS A MEMORY MAPPED BIT FOR BIT 


134B 




7070 ; 


DISPLAY OF 256 ACROSS BY 248 DOWN (256X248) 


134B 




7075 ; 




134B 




7080 ; 


EACH BLOCK OF 4X2 DOTS IS A SINGLE BYTE MEMORY 


134B 




7090 ; 


LOCATION. THE COMPOSITION OF THAT 4X2 BLOCK IS 


134B 




7100 ; 


AS SHOWN: 4 5 6 7 


134B 




7105 ; 


12 3 


134B 




7110 ; 




134B 




7120 ; 


THE FOLLOWING ROUTINES WILL EITHER PLOT THE 


134B 




7125 ; 


CO-ORDINATE (DRAW) OR CLEAR THE COORDINATE 


134B 




7130 ; 


(UNDRAW) . THE COORDINATE IS COUNTED FROM 


134B 




7135 ; 


THE UPPER LEFT CORNER OF THE SCREEN, AND IS 


134B 




7140 ; 


PASSED TO THE ROUTINES IN THE REGISTER 


134B 




7145 ; 


PAIR DE AS FOLLOWS: 


134B 




7150 ; 


D = X-COORDINATE (0 TO 256) 


134B 




7155 ; 


E = Y-COORDINATE (0 TO 248) 


134B 




7160 ; 




134B 




7400 ; 




134B 




7405 : 


DRAW ; ENTER WITH COORDINATE IN DE 


134B 




7410 ; 


DRAWS DOT, AND RETURNS MEM LOC IN HL 


134B 


C5 


7420 PUSH BC 


134C 


CD6313 


7430 CALL DOTA 


134F 


CDA413 


7440 CALL SETDOT 


1352 


CD7B13 


7450 CALL DOTB 


1355 


CI 


7460 POP BC 


1356 


C9 


7470 RET 


1357 




7480 j 




1357 




7485 : 


UNDRAW ; CLEARS THE DOT REQUESTED BY DE 


1357 




7490- j 




1357 


C5 


7500 PUSH BC 


1358 


CD6313 


7510 CALL DOTA 


135B 


CD8213 


7520 CALL UNDOT 


135E 


CD7B13 


7530 CALL DOTB 


1361 


CI 


7540 POP BC 


1362 


C9 


7550 RET 


1363 




7560 | 




1363 




7570 1 


:DOTA ;THIS ROUTINE DETERMINES THE ADDR 


1363 




7575 | 


: OF THE DOT'S BYTE AND PUTS IT IN HL 


1363 




7580 i 




1363 


7B 


7590 LD A,E 


1364 


OF 


7600 RRCA 


1365 


OF 


7610 RRCA 


1366 


OF 


7620 RRCA 


1367 


6F 


7630 LD L.A 


1368 


E61F 


7640 AND 1FH 


136A 


67 


7650 LD H,A 


136B 


7D 


7660 LD A,L 


136C 


E6C0 


7670 AND 0C0H 


136E 


6F 


7680 LD L,A 


136F 


7A 


7690 LD A,D 


1370 


CB3F 


7700 SRL A 


1372 


CB3F 


7710 SRL A 


1374 


B5 


7720 OR L 


1375 


6F 


7730 ] 


LiD L,A 


1376 


0100C0 


7740 LD BC, VIDEO ;Bl HAS VIDEO RAM ADDR 


1379 


09 


7750 ADD HL,BC ;ADD TO IT THE INCREMENT 


137A 


C9 


7760 RET ;HL POINTS TO PROPER BYTE 


137B 




7770 




137B 




7780 


:DOTB ;THIS ROUTINE EXPECTS HL=POINT ADDR ' 


137B 




7790 


| B=NEW BYTE WITH UPPER BITS modified 


137B 




7800 


| A=NEW BYTE WITH LOWER BITS MODIFIED. 


137B 




7810 


| USES LEAST SIGNIFICANT BIT IN E, 


137B 




7815 


| THE Y-COORDINATE, TO DETERMINE WHICH 


137B 




7820 


1 BYTE TO STORE IN VIDEO RAM. 


137B 




7830 




137B 


CB43 


7840 1 


3IT 0,E 


137D 


2001 


7850 i 


JR .NZ,DOTBl 


137F 


78 


7860 ] 


LiD A,B 


1380 


77 


7870 


:DOTBl LD (HL) , 


1381 


C9 


7880 ] 


RET 


1382 




7900 


• 
ff 


1382 




7910 


: UNDOT ;CLRS THE DOT IN THE BYTE POINTED 


1382 




7920 


j TO BY HL BASED ON THE TWO LEAST SIG- 


1382 




7930 


; NIFICANT BITS OF D (X-COORDINATE) 


1382 




7940 


USING REGISTERS A AND B f "N 


1382 




7950 


• (More__x 



170 Microcomputing, August 1981 



Listing 2 con 

1382 7E 
47 

CB42 
2809 
CB4A 
280E 
CBDF 
CBF8 
C9 

CB4A 
2 80A 
CBD7 
CBFO 
C9 

CBCF 
CBE8 
C9 

CBC7 
CBEO 
C9 



1383 

1384 

1386 

1388 

138A 

138C 

138E 

1390 

1391 

1393 

1395 

1397 

1399 

139A 

139C 

139E 

139F 

13A1 

13A3 

13A4 

13A4 

13A4 

13A4 

13A4 

13A5 

13A6 

13A8 

13AA 

13 AC 

13AE 

13B0 

13B2 

13B3 

13B5 

13B7 

13B9 

13BB 

13BC 

13BE 

13C0 



7E 

47 

CB42 

2809 

CB4A 

280E 

CB9F 

CBB8 

C9 

CB4A 

280A 

CB9 7 

CBBO 

C9 

CB8F 

CBA8 

C9 



13C1CB87 
13C3 CBAO 






13C5 

13C6 

13C6 

13C6 

13C6 

13C6 

13C6 

13C6 

13C6 

13C6 

13C6 

13C6 

13C6 

13C6 

13C6 

13C6 

13C6 

13C6 

13C6 

13C6 

13C6 

13C6 

13C6 

13C6 

13C6 

13C6 

13C7 

13C8 

13CB 

13CC 

13CC 

13CC 

13CF 

13D0 

13D1 

13D2 

13D4 

13D6 

13D7 

13D8 

13DA 

13DB 

13DB 

13DB 

13DC 

13DD 

13DE 

13DF 

13E1 

13E1 

13E1 

13E2 

13E3 



C9 



tinued. 

7960 
7970 
7980 
7990 
8000 
8010 
8020 
8030 
8040 
8050 
8060 
8070 
8080 
8090 
8100 
8110 
8120 
8130 
8140 
8150 
8160 
8170 
8180 
8190 
8200 
8210 
8215 
8220 
8230 
8240 
8250 
8260 
8270 
8280 
8290 
8300 
8310 
8320 
8330 
8340 
8350 
8360 
8370 
8380 
8600 
8610 
8620 
8630 
8640 
8650 
8660 
8670 
8680 
8690 
8700 
8710 
8715 
8720 
8730 
8740 
8750 
8760 
8770 
8775 
8780 
8790 



EL 
El 

CDCC13 
C9 



010000 

C5 

7A 

BC 

3807 

2004 

7B 

BD 

3801 

EB 



E5 
CI 
7B 
B9 
3828 



7A 
B8 
2812 



LD A, (HL) 

LD B,A 

BIT 0,D 

JR .Z f D0T3 

BIT 1,D 

JR .Z,D0T4 

SET 3, A 

SET 7,B 

RET 

:D0T3 BIT 1,D 

JR .Z,DOT5 

SET 2, A 

SET 6,B 

RET 

:DOT4 SET 1,A 

SET 5,B 

RET 

:D0T5 SET 0,A 

SET 4,B 

RET 



SETDOT ;SAME AS UNDOT, BUT CREATES THE 
DOT RATHER THAN REMOVING IT 



LD A, (HL) 
LD B,A 
BIT 0,D 
JR . Z,UNDOT3 
BIT 1,D 
JR . Z,UNDOT4 
RES 3, A 
RES 7,B 
RET 

:UNDOT3 BIT 1,D 
JR .Z,UNDOT5 
RES 2, A 
RES 6,B 
RET 

:UNDOT4 RES 1,A 
RES 5,B 
RET 
:UNDOT5 RES 0,A 



RES 

RET 



4,B 



* 



LINE ROUTINE THIS ROUTINE CALCULATES A POINT 

TO POINT LINE BETWEEN ANY TWO INPUTTED-POINTS . 
IT IS DESIGNED FOR A 256X248 MATRIX USING A 
STACK-ORIENTED ALGORITHM. THIS ROUTINE IS A 
MODIFICATION OF A ROUTINE FROM A 'BYTE* ARTICLE 
BY JOHN BEETEM IN THE OCTOBER 1980 ISSUE. 

THE BASIS OF THIS ALGORITHM IS THAT IT SUBDIVIDES 
A LINE BY TWO, RECURSIVELY, UNTIL THEY CAN PLOT 
I AS A SINGLE POINT. IT THEN REPEATS ITSELF ON 

OTHER LINE SEGMENTS UNTIL THE LINE IS FINISHED. 

40 BYTES OF STACK USAGE IS NEEDED FOR THIS ROUTINE. 

TWO ENTRY MODES ARE PROVIDED: 

MODE 1 'VECl* THE TWO ENDPOINTS ARE ENTERED 

ON THE STACK. PUSH THE POINTS ON THE STACK 

FOLLOWED BY THE RETURN ADDRESS. 

MODE 2 'VEC2' ENTER THE TWO ENDPOINTS 

AS FOLLOWS: 

POINT 1 IN DE (X COMPONENT IS 

POINT 2 IN HL (Y COMPONENT IS 



D) 
L) 



; 



CALL 
RET 



8800 
8900 :VEC1 
8910 POP DE 
8920 POP HL 
8930 
8940 
8950 
8960 
8970 
8980 
8990 
9000 
9010 
9020 
9030 
9040 
9050 
9060 
9070 
9080 
9090 
9100 
9110 
9120 
9130 
9140 
9150 
9160 
9170 
9180 



; HIGHER 
;GET 1ST 



;GET 
VEC2 

; RETURN 



LEVEL PROGRAM ENTRY POINT 
POINT 
2ND POINT 



TO HIGHER LEVEL CALLING PROGRAM 



:VEC2 
LD BC,0 
PUSH BC 
LD A,D 

H ;MAKE 

.C,NOXG 

.NZ,XNG 

A,E 

L 

.C,NOXG 



;BASE LINE DRAWING ROUTINE 
; STACK FINISHED FLAG 



CP 
JR 
JR 
LD 
CP 
JR 



DE THE SMALLER # 



:XNG EX 
:NOXG 



DE,HL 



; TRADE DE WITH HL 
; CHOOSE LOOP1 OR LOOP 2 
RELATIVE Y-COORDINATE 



BASED 
VALUES 



PUSH HL 

POP BC 

LD A,E 

CP C 

JR .C,LOOP2 



;BC=HL 



:LOOPl 
LD A,D 
CP B 
JR .Z,EQX1 



; COMPARE X- VALUES 




TYPRINTER450 



$2100 



45 CHAR/SEC DAISYWHEEL PRINTER/ 
TERMINAL. RS232; IDEAL FOR WORD 
PROCESSING; WILL SUPPORT DIABLO, 
QUME, AND NEC PROTOCOLS 



TYPRINTER550 



SAME AS ABOVE BUT 

55 CHAR/SEC PRINT SPEED 



$2300 
$1000 



QUME 

5 5 CHAR/SEC OEM PRINTER MECHANISM 

SHUGART8" FLOPPY 

DISK DRIVES $360 

SA800 SOFT-SECTORED 
SINGLE/DOUBLE DENSITY 

MICROSWITCH KEYBOARDS$85 



HALL EFFECT. ASCII MOD. 74SW12 



INTERFACE 



$325 



OEM DAISYWHEEL PRINTER INTER 
FACE. INTERFACES DIABLO OR 
QUME OEM PRINTER TO RS232 OR 
CENTRONICS PARALLEL 

RIBBONS $2.50 

DIABLO HYTYPE 1 OR QUME. CLOTH 
OR MULTI/STRIKE. 1 DOZ. MINIMUM 



COMPUTER IN NiMUCS. INC. 



211 WHITE WATER 
GREER, S.C. 29651 • (803)244-7872 



• 370 



System Software Design, Inc 

presents 

Ultimate Data System 

for 

The Rpple II* computer with 

• Applesoft* in ROM or language System* 

• 48K of RAM 

• 2 Disk Drives 

• Optional PYinter 

This easy-to-use data manager will moke 

• General Ledger 

• Moiling Lists 

• Inventory 

• Any other data related tasks 
quick and efficient to manoge 

Seek times under l /2 second for data lists 

up to 7S00 records 

Many more fast and powerful features 

Sngle copy $100 00 

Dealer terms ovoiloble 

Write to 

System Softuuare Design. Inc 

1 24 €leventh St 

A-ovidence. R.I 02906 



*TM of Apple Computer Inc 



• 367 



^ 







*S5P^ 



You've Written 
a Useful Program- 
We'd Like to Publish IV 



We want programs for 
INDUSTRIAL applications: 

JOB COST ESTIMATES 
INDUSTRIAL (PROCESS) CONTROL 
JOB TRACKING 
MACHINE SCHEDULING 

Get published and earn royalties! 
Write for our free Programmer's 
Kit today. 

INSTANT SOFTWARE, INC. ^75 
Submissions Dept. 
Peterborough, NH 03458 



'See List of Advertisers on page 194 



Microcomputing, August 1981 171 



Cal 
For 



Manuscripts 

Kilobaud Microcomputing is 
looking for business articles! 

Businessmen in all fields are be- 
ginning to take notice of the micro- 
computer. They are eager to know 
which computers, peripheral equip- 
ment and applications software will 
let them take full advantage of this 
new tool. What knowledge do you 
have to share? 

Here are the kinds of articles that 
we want you to write for us: 

• Are you a businessman with a 
system up and running? We want to 
know how it works. What were your 
expectations? Have they been ful- 
filled? Did you find the software that 
you wanted? What problems have 
you had? How did you overcome 
them? What recommendations do 
you have for other businessmen? 

• We want reviews from a busi- 
nessman's perspective of specific 
hardware and software. If you've re- 
cently bought a new product and 
want to tell others how great — or 
poor— it is, Microcomputing will 
provide you with a forum. 

• What programs have you written 
to meet your specific needs? Per- 
haps another businessman can use 
them, too. Even if he can't, your pro- 
gram may serve as a springboard 
for other ideas. 

• Perhaps you aren't using your mi- 
cro for business, but know a com- 
pany that is. Trot on down with your 
pencil and notebook, and find out 
what they're up to. While they might 
not have the time to write up their 
experiences, they might be more 
than willing to tell somebody else 
about them. And an outside obser- 
ver will often be able to see things 
with a unique and valuable perspec- 
tive. 

Don't worry if you're not a profes- 
sional writer. That's what we editors 
are here tor. And we'll be more than 
happy to send you a copy of our 
writer's guidelines. 

Send your manuscripts and cor- 
respondence to: 
Kilobaud Microcomputing 
Pine St. 
Peterborough, NH 03458 



Listing 2 continued. 












13E5 


C5 


9190 


PUSH BC ; SINCE Xl#X2, 


SAVE OLD 2ND POINT 


13E6 


80 


9200 


ADD A,B ; AS FUTURE 1ST POINT 




13E7 


IF 


9210 


RRA j COMPUTE 


X HALFWAY POINT 




13E8 


47 


9220 


LD B,A ; INSTALL 


AS NEW 2ND X 




13E9 


3C 


9230 


INC A ;INCR TO 


FORM 


X-MIDPOINT 




13EA 


67 


9240 


LD H,A ; INSTALL 


NEW X 


-MIDPOINT 




13EB 


7B 


9250 


LD A,E ;NOW Xl#X2, SO 


COMPARE Y 


VALUES 


13EC 


B9 


9260 


CP c 








13ED 


2804 


9270 


JR .Z,EQY1 ;JMP IF NEW 


Y-MID NOT 


NEEDED 


13EF 


81 


9280 


:NEQY1 ADD A,C ; SINCE 


Y1#Y2, 




13F0 


IF 


9290 


RRA ; COMPUTE 


NEW Y 


-MIDPOINT 




13F1 


4F 


9300 


LD C,A ;PUT INTC 


) C AND 




13F2 


OC 


9310 


INC C ;INCR TO 


FORM 


NEW Y2 




13F3 


6F 


9320 


:EQY1 LD L,A ; SINCE NEITHER X'S OR Y'S EQUAL 


13F4 


E5 


9330 


PUSH HL ;SAVE MIDPOINT 


AS FUTURE 


2ND POINT 


13F5 


18EA 


9340 


JR LOOP1 ; CONTINUE 


I ON DIFFERENT SEGMENT 


13F7 


7B 


9350 


:EQX1 LD A,E ; SINCE XI 


=X2, THEN COMPARE 


13F8 


B9 


9360 


CP C ; Y VALUES. 






13F9 


2804 


9370 


JR . Z,EQXY1 ;IF 


Y1=Y2 


, JMP AND PLOT 


13FB 


C5 


9380 


PUSH BC ; OTHERWISE, SAVE 2ND POINT AS FUTURE 


13FC 


62 


9390 


LD H,D ; 1ST POINT. 


MAKE MIDPOINT X=Xl 


13FD 


18F0 


9400 


JR NEQY1 








13FF 


CD4B13 


9410 


:EQXY1 CALL DRAW ; 


PLOT 


COORDINATES 


IN DE 


1402 


Dl 


9420 


POP DE ; RETRIEVE ANOTHER SEGMENT 


"S 1ST POINT 


1403 


7A 


9430 


LD A,D ; CHECK IP 


' STACK EMPTY 




1404 


B3 


9435 


OR E 








1405 


C8 


9440 


RET . Z ;DONE IF 


ZERO 






1406 


CI 


9450 


POP BC ; RETRIEVE ANOTHER SEGMENT 


"S 2ND POINT 


1407 


18D8 


9460 


JR LOOP1 ;JP BACK 


TO KEEP MAKING LINE 


1409 




9500 


• 
1 








1409 




9510 


:LOOP2 ;SAME INSTS 


! AS LOOP1 EXCEPT 


1 LINE 9680, 


1409 




9520 


SO THE REMARKS 


WILL BE OMMITTED. 


1409 


7A 


9530 


LD A,D 








140A 


B8 


9540 


CP B 








140B 


2812 


9550 


JR .Z,EQX2 








140D 


C5 


9560 


PUSH BC 








140E 


80 


9570 


ADD A,B 








140F 


IF 


9580 


RRA 








1410 


47 


9590 


LD B,A 








1411 


3C 


9600 


INC A 








1412 


67 


9610 


LD H,A 








1413 


7B 


9620 


LD A,E 








1414 


B9 


9630 


CP C 








1415 


2804 


9640 


JR . Z,EQY2 








1417 


81 


9650 


:NEQY2 ADD A,C 








1418 


IF 


9660 


RRA 








1419 


4F 


9670 


LD C,A 








141A 


3C 


9680 


INC A ;THIS STATEMENT 


IS DIFFERENT THAN LO 


14 IB 


6F 


9690 


:EQY2 LD L,A 








141C 


E5 


9700 


PUSH HL 








141D 


18EA 


9710 


JR LOOP 2 








141F 


7B 


9720 


:EQX2 LD A,E 








1420 


B9 


9730 


CP C 








1421 


2804 


9740 


JR . Z,EQXY2 








1423 


C5 


9750 


PUSH BC 








1424 


62 


9760 


LD H,D 








1425 


18F0 


9770 


JR NEQY2 








1427 


CD4B13 


9780 


:EQXY2 CALL DRAW 








142A 


Dl 


9790 


POP DE 








142B 


7A 


9800 


LD A,D 








142C 


B3 


9810 


OR E 








142D 


C8 


9820 


RET .Z 








142E 


CI 


9830 


POP BC 








142F 


18D8 


9840 


JR LOOP 2 








1431 


Dl 


10000 


POP DE 








1432 


CD4B13 


10010 


CALL DRAW 








1435 


C9 


10020 


RET 










0406 


AD VI 


115D ADVII 


116B 


ADVII I 


116F 


BACK1 10 8D 


BACKSP 1082 BELLS 


HOB 


BUFFER 


BFF0 


BUFHI 0004 


BUFLO 000 3 BUF)HL 


124C 


CAL CUR 


11A1 


CHAR2 1124 


CHAR4 1132 CHAR6 


1139 


CHARLD 


1146 


CHAROT 1116 


CHARS 12D9 CHARTR 


0007 


CHIP 


1320 


CLR1 


1214 


CLRLIN 1206 CLRMEM 


12A2 


CLRMM1 


12A8 


CLRROW 11F6 


CMDVCT 1058 COLUMN 


oooc 


CRR2 


1100 


CRRTN 10EA 


CURHI 0009 CURLO 


0008 


CURSLD 


12 1A 


CUR)HL 1276 


DE)VID 12 3E DOT3 


1391 


DOT4 


139A 


DOT5 


139F 


DOTA 


1363 DOTB 


137B 


DOTB1 


1380 


DOTS 


1328 


DOTS1 132F DOTS 2 


133A 


DRAW 


134B 


EQX1 


13F7 


EQX2 


14 IF EQXY1 


13FF 


EQXY2 


1427 


EQY1 


13F3 


EQY2 


141B EXIT 


107B 


FWD1 


10A6 


FWDSP 109B 


GRAPH 12 84 HL) BUF 


1245 


HL)CUR 


126F 


HL)HOM 1253 


HL)ROW 1261 HOME 


10D9 


HOMHI 


0006 


HOMLD 12 2C 


HOMLO 0005 HOM)HL 


125A 


INITBF 


12B0 


LAST4 10C1 


LASTRW 10 B 4 LOC 


1030 


LOOP1 


13E1 


LOOP2 1409 


LTTRS 129 4 MASK8K 


127D 


NEQY1 


13EF 


NEQY2 1417 


NEXT 4 10D5 NEXTRW 


10C5 


NOXG 


13DB 


PLOTTR 000D 


REGI 


1180 REGIII 


118E 


ROLLDN 


11DA 


ROLLUP 11B0 


ROWHI 00 0B ROWLO 


000A 


ROW)HL 


1268 


RWMAXH 0007 


RWMAXL 00 30 SETDOT 


13A4 


SPACE 


1205 


SPARE 0000 


UNDOT 1382 UNDOT3 


13B3 


UNDOT 4 


13BC 


UNDOT5 13C1 


UNDRAW 1357 VEC1 


13C6 


VEC2 


13CC 


VECTOR 106D 


VIDEO CO 00 VIDHI 


0002 


VIDLO 


0001 


XNG 


13DA 


• 
• 











172 Microcomputing, August 1981 




• TRS-80 ASSEMBLY LANGUAGE— BK1217 — by 
Hubert S. Howe, Jr. This book incorporates into a 
single volume all the pertinent facts and information 
you need to know to program and enjoy the TRS-80. In- 
cluded are clear presentations of all introductory con- 
cepts, completely tested practical programs and sub- 
routines, details of ROM and RAM and disk operating 
systems, plus comprehensive tables, charts and ap- 
pendices. Suitable for the first time user or more ex- 
perienced users. $9.95.* 

• INSIDE LEVEL II— BK1183— For machine language 
programmers! This is a comprehensive reference 
guide to the Level II ROMs, allowing easy utilization of 
the sophisticated routines they contain. It concisely 
explains set-ups, calling sequences, variable passage 
and I/O routines. Part II presents an entirely new com- 
posite program structure which unloads under the 
SYSTEM command and executes in both BASIC and 
machine code with the speed and efficiency of a com- 
piler. Special consideration is given to disk systems. 
$15.95.* 

• PROGRAMMING THE Z-80— BK1122— by Rodnay 
Zaks. Here is assembly language programming for the 
Z-80 presented as a progressive, step-by-step course. 
This book is both an educational text and a self- 
contained reference book, useful to both the beginning 
and the experienced programmer who wish to learn 
about the Z-80. Exercises to test the reader are includ- 
ed. $14.95.* 

• Z-80 SOFTWARE GOURMET GUIDE AND COOK- 
BOOK— BK1045— by Nat Wadsworth. Scelbi's newest 
cookbook! This book contains a complete description 
of the powerful Z-80 instruction set and a wide variety 
of programming information. Use the author's ingre- 
dients including routines, subroutines and short pro- 
grams, choose a time-tested recipe and start cooking! 
$16.99.* 

• Z-80 ASSEMBLY LANGUAGE PROGRAMMING — 

BK1177—by Lance A. Leventhal. This book thoroughly 
covers the Z-80 instruction set, abounding in simple 
programming examples which illustrate software de- 
velopment concepts and actual assembly language 
usage. Features include Z-80 I/O devices and interfac- 
ing methods, assembler conventions, and compari- 
sons with 8080A/8085 instruction sets and interrupt 
structure. $16.99.* 



• VOL. I COMPONENT TESTERS— LB7359-. . .how 
to build transistor testers (8), diode testers (3), IC test- 
ers (3), voltmeters and VTVMs (9), ohmmeters (8 differ- 
ent kinds), inductance (3), capacity (9), Q measure- 
ment, crystal checking (6), temperature (2), aural 
meters for the blind (3) and all sorts of miscellaneous 
data on meters. . .using them, making them more ver- 
satile, making s\andaroa. \rv*a\uable book. $4.95.* 

• VOL II AUDIO FREQUENCY TESTERS- LB7360- 
. . .jam packed with all kinds of audio frequency test 
equipment. If you're into SSB, RTTY, SSTV, etc., this 
book is a must for you. . .a good book for hi-fi addicts 
and experimenters, too! $4.95.* 

• VOL III RADIO FREQUENCY TESTERS— LB 7361 — 

Radio frequency waves, the common denominator of 
Amateur Radio. Such items as SWR, antenna im- 
pedance, line impedance, rf output and field strength; 
detailed instructions on testing these items includes 
sections on signal generators, crystal calibrators, grid 
dip oscillators, noise generators, dummy loads and 
much more. $4.95.* 

• VOL IV IC TEST EQUIPMENT— LB7362— Become a 
troubleshooting wizard! In this fourth volume of the 73 
TEST EQUIPMENT LIBRARY are 42 home construction 
projects for building test equipment to work with your 
ham station and in servicing digital equipment. Plus a 
cumulative index for all four volumes for the 73 TEST 
EQUIPMENT LIBRARY. $4.95.* 



PROGRAMMING 



The Microprocessor Software Engineering Series by 

John Zarrella provides common sense descriptions of 
advanced computer system topics for engineers, pro- 
grammers and development managers. Each volume is 
a self-contained review of a software engineering 
topic, explaining fundamental concepts in easy-to-un- 
derstand language and describing sophisticated soft- 
ware tools and techniques. Detailed glossary of tech- 
nical jargon is included in each volume. This series will 
help you find the solutions to your software problems. 

• OPERATING SYSTEMS: CONCEPTS AND PRINCI- 
PLES— BK1 193— Presents an overview of the basic op- 
erating system types, their components and capabil- 
ities. $7.95.* 

• WORD PROCESSING AND TEXT EDITING — BK1 194 

— Provides a firm basis for understanding word pro- 
cessing terminology and for comparing systems. 
$7.95.* 

• SYSTEM ARCHITECTURE- BK1 195 —Presents a 
detailed overview of advanced computer system 
design including object architecture and capability- 
based addressing. $9.95.* 



* 



6502 



•* 



• THE APPLE II USER'S GUIDE— BK1220— by Lon 

Poole, Martin McNiff, and Steven Cook. This guide is 
the key to unlocking the full power of your Apple II or 
Apple II Plus. Topics include: "Applesoft and Integer 
BASIC Programming"— especially how to make the 
best use of Apple's sound, color and graphics capabili- 
ties. "Machine Level Programming," "Hardware 
Features"— which covers the disk drive and printer, 
and "Advanced Programming" — describing high 
resolution graphics techniques and other advanced 
applications. Well organized and easy to use. $15.00* 

• PROGRAMMING THE 6502 (Third Edition)— BK1 005 

— Rodnay Zaks has designed a self-contained text to 
learn programming, using the 6502. It can be used by a 
person who has never programmed before, and should 
be of value to anyone using the 6502. The many exer- 
cises will allow you to test yourself and practice the 
concepts presented. $12.95.* 

• 6502 APPLICATIONS BOOK— BK1006— Rodnay Zaks 
presents practical-application techniques for the 6502 
microprocessor, assuming an elementary knowledge of 
microprocessor programming. You will build and design 
your own domestic-use systems and peripherals. Self- 
test exercises included. $12.95.* 

• 6502 ASSEMBLY LANGUAGE PROGRAMMING — 

BK1176 — by Lance A. Leventhal. This book provides 
comprehensive coverage of the 6502 microprocessor 
assembly language. Leventhal covers over 80 program- 
ming examples from simple memory load loops to 
complete design projects. Features include 6502 as- 
sembler conventions, input/output devices and inter- 
facing methods, and programming the 6502 interrupt 
system. $16.99.* 

• 6502 SOFTWARE GOURMET GUIDE AND COOK- 
BOOK— BK1055— by Robert Findley. This book intro- 
duces the BASIC language programmer into the realm 
of machine-language programming. The description of 
the 6502 structure and instruction set, various 
routines, subroutines and programs are the ingredi- 
ents in this cookbook. "Recipes" are included to help 
you put together exactly the programs to suit your 
taste. $12.95.* 



•MICROCOMPUTING CODING SHEETS Microcom- 
puting s dozen or so programmers wouldn't try to work 
without these handy scratch pads, which help prevent 
the little errors that can cost hours and hours of pro- 
gramming time. Available for programming is Assem- 
bly/Machine Language (PD1001), which has columns 
tor address, instruction (3 bytes), source code (label 
/° D P n, C ^' ?P e I^ n< il and comments; and for BASIC 
to *b T . wh,ch ,s 72 columns wide. 50 sheets to a pad. 



8080/8080A-6800- 

• 6809 MICROCOMPUTER PROGRAMMING AND 
INTERFACING— BK1215— by Andrew C. Staugaard, 
Jr. Getting involved with Tandy's new Color Computer? 
If so, this new book from the Blacksburg Group will 
allow you to exploit the awesome power of the 
machine's 6809 microprocessor. Detailed information 
on processor architecture, addressing modes, register 
operation, data movement, arithmetic logic opera- 
tions, I/O and interfacing is provided, as well as a 
review section at the end of each chapter. Four appen- 
dices are included covering the 6809 instruction set, 
specification sheets of the 6809 family of processors, 
other 6800 series equipment and the 6809/6821 
Peripheral Interface Adapter. This book is a must for 
the serious Color Computer owner. $13.95.* 

^•68000 MICROPROCESSOR HANDBOOK— BK1216 
—by Gerry Kane. Whether you're currently using the 
68000, planning to use it, or simply curious about one 
of the newest and most powerful microprocessors, 
this handbook has all the answers. A clear presenta- 
tion of signal conversions, timing diagram conven- 
tions, functional logic, three different instruction set 
tables, exception processing, and family support 
devices provides more information about the 68000 
than the manufacturer's data sheets. A stand alone 
reference book which can also be used as a supple- 
ment to An Introduction to Microcomputers: Vol. 2 — 
Some Real Microprocessors. $6.99.* 

• 8080A/8085 ASSEMBLY LANGUAGE PROGRAM- 
MING— by Lance Leventhal— BK1004— Assembly lan- 
guage programming for the 8080A/8085 is explained 
with a description of the functions of assemblers and 
assembly instructions, and a discussion of basic soft- 
ware development concepts. Many fully debugged, 
practical programs are included as is a special section 
on structured programming. $15.99.* 

• 8080 SOFTWARE GOURMET GUIDE AND COOK- 
BOOK— BK1 102— If you have been spending too much 
time developing simple routines for your 8080, try this 
new book by Scelbi Computing and Robert Findley. De- 
scribes sorting, searching, and many other routines for 
the 8080 user. $12.95.* 

—COOKBOOKS 

• CMOS COOKBOOK— BK101 1— by Don Lancaster. 
Details the application of CMOS, the low power logic 
family suitable for most applications presently 
dominated by TTL. Required reading for every serious 
digital experimenter! $10.50.* 

• TVT COOKBOOK— BK1064— by Don Lancaster. De- 
scribes the use of a standard television receiver as a 
microprocessor CRT terminal. Explains and describes 
character generation, cursor control and interface in- 
formation in typical, easy-to-understand Lancaster 
style. $9.95.* 

• TTL COOKBOOK— BK1063— by Don Lancaster. Ex- 
plains what TTL is, how it works, and how to use it. Dis- 
cusses practical applications, such as a digital coun- 
ter and display system, events counter, electronic 
stopwatch, digital voltmeter and a digital tachometer. 
$9.50.* 



*Use the order card in the back of this magazine or itemize your order on a separate 
piece of paper and mail to Kilobaud Microcomputing Book Department • Peterborough 
NH 03458. Be sure to include check or detailed credit card information. 



No C.O.D. orders accepted. All orders add $1 .50 handling. Please allow 4-6 weeks for 
delivery. Questions regarding your order? Please write to Customer Service at the 
above address. 



PRICES SUBJECT TO CHANGE WITHOUT NOTICE 



*new 



FOR TOLL FREE ORDERING CALL 1-800-258-5473 



BASIC & PASCAL 



BUSINESS 



^Y^#£ 




■ A IklTDf 



• INTRODUCTION TO TRS-80 LEVEL II BASIC AND 
COMPUTER PROGRAMMING-BK1219— by Michael 
P. Zabinski. Written by an experienced educator, this is 
the book for those beginners who want to learn about 
computers without having to become an expert. It has 
practical programs, useful line-by-line comments, ex- 
cellent flowcharts accompanied by line numbers and 
over 200 exercises which help the reader assess prog- 
ress, reinforce comprehension, and provide valuable 
practical experience. $10.95.* 

• 50 BASIC EXERCISES— BK1 192— by J. P. Lamoitier. 
This book is structured around the idea that the best 
way to learn a language is through actual practice. It 
contains 50 completely explained exercises: state- 
ment and analysis of the problem, flowcharts, pro- 
grams and actual runs. Program subjects include 
mathematics, business, games, and operations re- 
search, and are presented in varying levels of diffi- 
culty. This format enables anyone to learn BASIC rap- 
idly, checking their progress at each step. $12.95* 

• THE BASIC HANDBOOK— BK1 174— by David Lien. 
This book is unique. It is a virtual ENCYCLOPEDIA of 
BASIC. While not favoring one computer over another, 
it explains over 250 BASIC words, how to use them and 
alternate strategies. If a computer does not possess 
the capabilities of a needed or specified word, there 
are often ways to accomplish the same function by us- 
ing another word or combination of words. That's 
where the HANDBOOK comes in. It helps you get the 
most from your computer, be it a "bottom-of-the-line" 
micro or an oversized monster. $14.95.* 



• LEARNING LEVEL II — BK1175— by David Lien. Writ- 
ten especially for the TRS-80, this book concentrates 
on Level II BASIC, exploring every important BASIC 
language capability. Updates are included for those 
who have studied the Level I User's Manual. Sections 
include: how to use the Editor, dual cassette opera- 
tion, printers and peripheral devices, and the conver- 
sion of Level I programs to Level II. $15.95.* 

• BASIC BASIC (2ND EDITION)— BK1026— by James 
S. Coan. This is a textbook which incorporates the 
learning of computer programming using the BASIC 
language with the teaching of mathematics. Over 100 
sample programs illustrate the techniques of the BA- 
SIC language and every section is followed by practi- 
cal problems. This second edition covers character 
string handling and the use of data fi!es. $10.50.* 

• ADVANCED BASIC— BK1000— Applications, includ- 
ing strings and files, coordinate geometry, area, se- 
quences and series, simulation, graphing and games. 
$10.75*. 

• SIXTY CHALLENGING PROBLEMS WITH BASIC 
SOLUTIONS (2nd Edition)— BK1073— by Donald 
Spencer, provides the serious student of BASIC pro- 
gramming with interesting problems and solutions. No 
knowledge of math above algebra required. Includes a 
number of game programs, as well as programs for 
financial interest, conversions and numeric manipula- 
tions. $6.95.* 



PASCAL— BK1 188— by Paul M. Chirlian. Professor 
Chilian's textbook combines a simple approach to the 
PASCAL language with comprehensive coverage on 
how a computer works, how to use a flowchart, work- 
ing from a terminal as well as batch operation and 
debugging. Special attention is paid to idiosyncrasies 
of the language and syntax flowcharts abound for the 
convenience of the experienced programmer. Well in- 
dexed. $12.95* 

• INTRODUCTION TO PASCAL— BK1 189— by Rodnay 
Zaks. A step-by-step introduction for anyone wanting 
to learn the language quickly and completely. Each 
concept is explained simply and in a logical order. All 
features of the language are presented in a clear, easy- 
to-understand format with exercises to test the reader 
at the end of each chapter. It describes both standard 
PASCAL and UCSD PASCAL, the most widely used 
dialect for small computers. No computer or program- 
ming experience is necessary. $14.95.* 



• PROGRAMMING IN PASCAL— BK1 140— by Peter 
Grogono. The computer programming language 
PASCAL was the first language to embody in a coher- 
ent way the concepts of structured programming, 
which has been defined by Edsger Dijkstra and C.A.R. 
Hoare. As such, it is a landmark in the development of 
programming languages. PASCAL was developed by 
Niklaus Wirth in Zurich; it is derived from the language 
ALGOL 60 but is more powerful and easier to use. 
PASCAL is now widely accepted as a useful language 
that can be efficiently implemented, and as an ex- 
cellent teaching tool. It does not assume knowledge of 
any other programming language; it is therefore suit- 
able for an introductory course. $12.95.* ^ 



• PAYROLL WITH COST ACCOUNTING — IN BASIC— 

BK1001— by L. Poole & M. Borchers, includes program 
listings with remarks, descriptions, discussions of the 
principle behind each program, file layouts, and a com- 
plete user's manual with step-by-step instructions, 
flowcharts, and simple reports and CRT displays. Pay- 
roll and cost accounting features include separate 
payrolls for up to 10 companies, time-tested interac- 
tive data entry, easy correction of data entry errors, job 
costing (labor of distribution), check printing with full 
deduction and pay detail, and 16 different printed re- 
ports, including W-2 and 941 (in CBASIC). $20.00.* 

• SOME COMMON BASIC PROGRAMS— BK1053— 
published by Adam Osborne & Associates, Inc. Perfect 
for non-technical computerists requiring ready-to-use 
programs. Business programs, plus miscellaneous 
programs. Invaluable for the user who is not an ex- 
perienced programmer. All will operate in the stand- 
alone mode. $14.99 paperback. 

• PIMS: PERSONAL INFORMATION MANAGEMENT 

SYSTEM— BK1009— Learn how to unleash the power 
of a personal computer for your own benefit in this 
ready-to-use data-base management program. 
$11.95.* 

-MONEYMAKING— 



GAMES 



\ 



'&J&*°2£t 



• 40 COMPUTER GAMES— BK7381 — Forty games in all 
in nine different categories. Games for large and small 
systems, and even a section on calculator games. Many 
versions of BASIC used and a wide variety of systems 
represented. A must for the serious computer games- 
man. $7.95* 

• BASIC COMPUTER GAMES— BK1074— Okay, so 
once you get your computer and are running in BASIC, 
then what? Then you need some programs in BASIC, 
that's what. This book has 101 games for you from very 
simple to real buggers. You get the games, a descrip- 
tion of the games, the listing to put in your computer 
and a sample run to show you how they work. Fun. Any 
one game will be worth more than the price of the book 
for the fun you and your family will have with it. $7.50.* 

• MORE BASIC COMPUTER GAMES— BK1182 — 
edited by David H. Ahl. More fun in BASIC! 84 new 
games from the people who brought you BASIC Com- 
puter Games. Includes such favorites as Minotaur(bat- 
tle the mythical beast) and Eliza (unload your troubles 
on the doctor at bargain rates). Complete with game 
description, listing and sample run. $7.50.* 

• WHAT TO DO AFTER YOU HIT RETURN— BK1071 — 

PCC's first book of computer games. . .48 different 
computer games you can play in BASIC. . .programs, 
descriptions, many illustrations. Lunar Landing, Ham- 
murabi, King, Civel 2, Qubic 5, Taxman, Star Trek, 
Crash, Market, etc. $10.95.* 







mih eMon 






c on>. 



**//< 
















"*«*. 






• HOW TO MAKE MONEY WITH COMPUTERS— 

BK1003— In 10 information-packed chapters, Jerry 
Felsen describes more than 30 computer-related, 
money-making, high profit, low capital investment op- 
portunities. $15.00.* 

• HOW TO SELL ANYTHING TO ANYBODY— BK7308— 
According to The Guinness Book of WorJd Records, \he 
author, Joe Girard, is "the world's greatest salesman." 
This book reveals how he made a fortune— and how you 
can, too. $2.25.* 

• THE INCREDIBLE SECRET MONEY MACHINE- 

BK1 178— by Don Lancaster. A different kind of "cook- 
book" from Don Lancaster. Want to slash taxes? Get 
free vacations? Win at investments? Make money from 
something that you like to do? You'll find this book 
essential to give you the key insider details of what is 
really involved in starting up your own money machine. 
$5.95.* 



* Use the order card in the back of this magazine or itemize your order on a separate No C.O.D. orders accepted. All orders add $1 .50 handling. Please allow 4-6 weeks for 
piece of paper and mail to Kilobaud Microcomputing Book Department • Peterborough delivery. Questions regarding your order? Please write to Customer Service at the 
NH 03458. Be sure to include check or detailed credit card information. above address. 

PRICES SUBJECT TO CHANGE WITHOUT NOTICE 



FOR TOLL FREE ORDERING CALL 1-800-258-5473 



INTRODUCTORY 










7;J£ r4£ *t 

HOBBY 
COITiPUTERS 







• UNDERSTANDING AND PROGRAMMING MICRO- 
COMPUTERS— BK7382— A valuable addition to your 
computing library. This two-part text includes the best 
articles that have appeared in 73 and Kilobaud 
Microcomputing magazines on the hardware and soft- 
ware aspects of microcomputing. Well-known authors 
and well-structured text helps the reader get involved. 
$10.95* 

• SOME OF THE BEST FROM KILOBAUD MICROCOM- 
PUTING— BK731 1 —A collection of the best articles that 
have appeared in Kilobaud MICROCOMPUTING. Includ- 
ed is material on the TRS-80 and PET systems, CP/M the 
8080/8085/Z-80 chips, the ASR-33 terminal. Data base 
management, word processing, text editors and file 
structures are covered too. Programming techniques 
and hard-core hardware construction projects for 
modems, high speed cassette interfaces and TVTs are 
also included in this large format, 200 plus page edition 
$10.95.* 



• YOUR FIRST COMPUTER— BK1191 — by Rodnay 
Zaks. Whether you are using a computer, thinking 
about using one or considering purchasing one, this 
book is indispensable. It explains what a computer 
system is, what it can do, how it works and how to 
select various components and peripheral units. It is 
written in everyday language and contains invaluable 
information for the novice and the experienced pro- 
grammer. (The first edition of this book was published 
under the title "An Introduction to Personal and 
Business Computing".) $7.95* 



• MICROPROCESSOR INTERFACING TECHNIQUES 

— BK1037— by Austin Lesea & Rodnay Zaks— will 
teach you how to interconnect a complete system and 
interface it to all the usual peripherals. It covers hard- 
ware and software skills and techniques, including the 
use and design of model buses such as the IEEE 488 or 
S-100. $15.95.* 



• HOBBY COMPUTERS ARE HERE! — BK7322— If you 
want to come up to speed on how computers work. . . 
hardware and software. . this is an excellent book. It 
starts with fundamentals and explains the circuits, and 
the basics of programming, along with a couple of TVT 
construction projects, ASCII-Baudot, etc. This book has 
the highest recommendations as a teaching aid. $4.95.* 

• THE NEW HOBBY COMPUTERS-BK7340-This 
book takes it from where "HOBBY COMPUTERS ARE 
HERE!" leaves off, with chapters on Large Scale Integra- 
tion, how to choose a microprocessor chip, an introduc- 
tion to programming, low cost I/O for a computer, com- 
puter arithmetic, checking memory boards... and 
much, much more! Don't miss this tremendous value' 
Only $4.95.* 

• AN INTRODUCTION TO MICROCOMPUTERS, VOL. 

— BK1 130— The Beginner's Book— Written for readers 
who know nothing about computers— for those who 
have an interest in how to use computers— and for 
everyone else who must live with computers and 
should know a little about them. The first in a series of 
4 volumes, this book will explain how computers work 
and what they can do. Computers have become an in- 
tegral part of life and society. During any given day you 
are affected by computers, so start learning more 
about them with Volume 0. $7.95.* 

• VOL. I— BK1030— 2nd Edition completely revised. 

Dedicated to the basic concepts of microcomputers 
and hardware theory. The purpose of Volume I is to 
give you a thorough understanding of what microcom- 
puters are. From basic concepts (which are covered in 
detail), Volume I builds the necessary components of a 
microcomputer system. This book highlights the dif- 
ference between minicomputers and microcomputers 
$12.99.* 

• VOL. II — BK1040 (with binder)— Contains descrip- 
tions of individual microprocessors and support 
devices used only with the parent microprocessor. 
Volume II describes all available chips. $31.99* 

• VOL. Ill — BK1133 (with binder)— Contains descrip- 
tions of all support devices that can be used with any 
microprocessor. $21.99* 



SPECIAL INTERESTS 



TltS-SO I##SI% 

^OTHOTAWSTEfi 



<*?* 




• TRS-80 DISK AND OTHER MYSTERIES— BK1 181 — 

by Harvard C. Pennington. This is the definitive work 
on the TRS-80 disk system. It is full of detailed "How 
to" information with examples, samples and in-depth 
explanations suitable for beginners and professionals 
alike. The recovery of one lost file is worth the price 
alone. $22.50.* 



• MICROSOFT BASIC DECODED AND OTHER 
MYSTERiES— BK1186— by James Farvour. From the 
company that brought you TRS-80 DISK AND OTHER 
MYSTERIES*. Contains more than 6500 lines of com- 
ments for the disassembled Level II ROMs, six addi- 
tional chapters describing every BASIC subroutine, 
with assembly language routines showing how to use 
them. Flowcharts for all major routines give the reader 
a real insight into how the interpreter works. $29.50. 



THE CUSTOM TRS-80 AND OTHER MYSTERIES— 

BK1218— by Dennis Kitsz. More than 300 pages of 
TRS-80 customizing information. With this book you'll 
be able to explore your computer like never before. 
Want to turn an 8 track into a mass storage unit? In- 
dividual reverse characters? Replace the BASIC 
ROMs? Make Music? High speed, reverse video, Level I 
and Level II? Fix it if it breaks down? All this and much, 
much more. Even if you have never used a soldering 
iron or read a circuit diagram, this book will teach you 
how! This is the definitive guide to customizinq vour 
80! $29.95.* 

• BASIC FASTER AND BETTER AND OTHER MYS- 
TERIES— BK1221— by Lewis Rosenfelder. You don't 
have to learn assembly language to make your pro- 
grams run fast. With the dozens of programming tricks 
and techniques in this book you can sort at high speed 
swap screens in the twinkling of an eye, write INKEY 
routines that people think are in assembly language 
and add your own commands to BASIC. Find out how 
to write elegant code that makes your BASIC really 
hum, and explore the power of USR calls. $22.50 * 
Available end of August. 

• THE CP/M HANDBOOK (with MP/M)— BK1187— by 
Rodnay Zaks. A complete guide and reference hand- 
book for CP/M— the industry standard in operating 
systems. Step-by-step instruction for everything from 
turning on the system and inserting the diskette to cor- 
rect user discipline and remedial action for problem 
situations. This also includes a complete discussion 
of all versions of CP/M up to and including 2.2, MP/M 
and CDOS. $14.95*. 

• INTRODUCTION TO TRS-80 GRAPHICS-BK1180- 

by Don Inman. Dissatisfied with your Level I or Level II 
manual's coverage of graphics capabilities? This well- 
structured book (suitable for classroom use) is ideal 
for those who want to use all the graphics capabilities 
built into the TRS-80. A tutorial method is used with 
many demonstrations. It is based on the Level I but all 
material is suitable for Level II use. $8 95 * 




• TOOLS & TECHNIQUES FOR ELECTRONICS— 

BK7348— by A. A. Wicks is an easy-to-understand book 
written for the beginning kit builder as well as the ex- 
perienced hobbyist. It has numerous pictures and 
descriptions of the safe and correct ways to use basic 
and specialized tools for electronic projects as well as 
specialized metal working tools and the chemical aids 
which are used in repair shops. $4.95.* 

• HOW TO BUILD A MICROCOMPUTER— AND REALLY 
UNDERSTAND IT— BK7325— by Sam Creason. The elec- 
tronics hobbyist who wants to build his own microcom- 
puter system now has a practical "How-To" guidebook. 
This book is a combination technical manual and pro- 
gramming guide that takes the hobbyist step-by-step 
through the design, construction, testing and debugging 
of a complete microcomputer system. Must reading for 
anyone desiring a true understanding of small computer 
systems. $9.95.* 



•Use the order card in the back of this magazine or itemize your order on a separate 
piece of paper and mail to Kilobaud Microcomputing Book Department • Peterborough 
NH 03458. Be sure to include check or detailed credit card information. 



No C.O.D. orders accepted. All orders add $1 .50 handling. Please allow 4-6 weeks for 
delivery. Questions regarding your order? Please write to Customer Service at the 
above address. 



PRICES SUBJECT TO CHANGE WITHOUT NOTICE 



FOR TOLL FREE ORDERING CALL 1-800-258-5473 



p^%[% TUC IEEE CPU z hard| Y n ©^s any introduction-since the day we introduced this Z80 # 

P^/K |nt IEEE workhorse, professional systems integrators have made it the CPU board of choice 

^ ^ ^ ^■■^^ for nj n performance 8 bit systems. 

AQA /S-li jC J II IS" What Is new is the price: Until September 30th, CPU Z (assembled) is yours for an 

**"**/ ** *'+*'%* B#WW- amazingly low 5199! 

^ n i ■ -v m^ aiaai For new systems, CPU Z's superior flexibility (24 bit addressing, sockets for adding 

^rU £ lOl OItT! up to 8 Kbytes of on-board RAM or ROM, 4 MHz operation, on-board fully maskable 

interrupts, and much more) puts it miles ahead of the competition. For upgrading 

older systems, CPU Z is backward compatible with most S-lOO mainframes, down to a switch selectable choice of 2 or 4 MHz 

operation-there's even a plug that accepts the connector from an IMSAI front panel. 

Here's one deal you can't afford to pass up. . .visit your local CompuPro representative, or order direct from the factory, but hurry 

-quantities are limited. 



FOR MEMORY EXPANSION: 
EIGHT 16K DYNAMIC RAMS 

for $19.95! 



You can't beat the quality or the price-, eight low 
power, high speed dynamic RAMs, suitable for 
expanding memory in TRS-80* -I, -II, and -III (color 
computer too); H89; Apple; newer PETs; etc. Backed 
by 1 year limited warranty. Add $3 for two DIP shunts 
plus TRS-80 conversion instructions. 



IEEE 696/SlOO COMPONENT LEVEL PRODUCTS 



DISK EQUIPMENT/SYSTEMS 

Disk 1 Controller Board Ultra-fast operation, thanks to 
properly implemented DMA (with arbitration) and data 
transfer that's independent of CPU speed. Handles up to four 
8" or 5.25" floppy disk drives, single or double-sided, single or 
double density (soft sectored). Includes BIOS for CP/M-80 
(provided on 8" soft sectored diskette). Manual only: $25. A/T 
$495 CSC $595. 

Available only with Disk 1 purchase: CP/M-80 diskette with 
documentation, $175; CP/M-86 diskette with documentation, 
$300. 

Complete Dual Disk Drive Sy item With Disk 1 board, 
desktop dual drive enclosure with Shugart SA-800 series 
drives, disk cables, and power supply cable. Also includes 
CP/M-80. Introductory special: $2195. 

COMPUTER ENCLOSURES 

Computer Enclosure 2. With fused, constant voltage 
power supply ( + 8V at 25A, + 16V at 3A, and -16V at 3A); line 
filter; 20 slot shielded /active terminated motherboard; and 
rugged, all-metal enclosure that minimizes interference 
problems. $825 desk top version, $895 rack mount version. 

Computer Enclosure 1. Same as CE2, but enclosure only. 
$289 desktop, $329 rack mount (slides included). 



INTERFACERS 



Interfacer 1. Two RS-232 serial ports, with full handshaking 
and independently selectable Baud rates. $199 Unkit, $249 
A/T, $324 CSC. 

Interfacer 2. Three full duplex parallel ports, plus one serial 
port. $199 Unkit, $249 A/T, $324 CSC. 

Interfacer 3-5. Five RS-232 serial ports (2 synchronous/ 
asyncronous, 3 asynchronous) with full handshaking. $599 A/T, 
$699 CSC. 

Interfacer 3-8. Eight full RS-232 serial ports (2 synchronous/ 
asynchronous. 6 asynchronous). Ideal for multi-user/multi- 
terminal systems. $699 A/T, $849 CSC. 



MEMORY BOARDS 



48K/64K RAM 1 7 Static Memory Board. Exceptionally low 
power (4W max, 2W typ for 64K), high speed static memory- 
runs faster, cooler, and handles DMA better in ultra-high speed 
systems than competing dynamic memory boards. RAM 17- 
48K: $1048 A/T, $1198.50 CSC. RAM 17-64K: $1095 Unkit, 
$1395 A/T, $1595 CSC. 

96K/128K RAM 21 Static Memory Board. Exceptionally low 
power, high speed static memory. RAM 21-96K and RAM 21- 
128 K: Price upon request. 

2708 EPROM Board. This board is the way to store often 
used routines or pieces of software. $85 Unkit, $135 A/T, $195 
CSC (2708s not included). 

DOCUMENTATION 

User manuals are available for all products for $5, with the 
following exceptions: Interfacer 3, $10; Disk Controller, $25; 
System Support 1, $20. Also available: "CompuPro Product 
User Manuals: 1975-1980". 250+ pages on all Godbout/ 
CompuPro products up through 1980. Excellent for evaluating 
the innovative engineering behind CompuPro products, or 
studying the nuts and bolts of high speed computer operation. 
$20 plus shipping. 



FLASHI Phase l's single- and multi-user Oasis operating system 
is now available configured for Disk 1. See next month for full 
details and prices. 



Most CompuPro products are available in Unkit form. Assembled/Tested, or qualified 
under the high-reliabilrty Certified System Component (CSC) program (2CO hour burn-in 
more). Not* Unktts are not intended for novices, as de-bugging may be required due to 
problems such as IC Infant mortality. Factory service Is available for Unklts at a flat service 
charge. 

TERMS: Prices shown do not include dealer installation and support services Cal res add tax. 
Allow at least 5% shipping excess refunded. Orders under $15 add $2 handling. VISA* and 
Mastercard* orders ($25 min) call our 24 hour order desk at (415) 562-0636. Include street 
address for UPS delivery. Prices and specifications subject to change without notice. 

•tfGAL CORNER: Z-K3 It a r»gjtt«r«d trademark of Btog; CP/M la a reentered trademark of Digital Retearctv TRS-SO It a 
tiodomof k of the Tandy Corporation. 



If your computer store doesn't stock CompuPro products yet, 

call (415) 562-0636 and we'll tell you who does. 




uPro" 



»^42 
division of 




BOX 2355, OAKLAND AIRPORT, CA 94614 (415) 562-0636 



176 Microcomputing, August 1981 



TRS-80 
SERIAL I/O 

• Can input into basic 

• Can use LUST and 
LPRINT to output, or 
output continuously • 
RS-232 compatible • 
Can be used with or 
without the expansion 
bus • On board switch 
selectable baud rates 
of 1 1 0. 1 50, 300, 600, 
1200, 2400. parity or 
no parity odd or even, 
5 to 8 data bits, and 1 
or 2 stop bits. D.T.R. 
line • Requires +5. 
-12VDC •Board only 
$19.95 Part No. 8010. 
with parts $76. 69 Part 
No. 801 OA. assembled 
$98.25 Part No. 8010 
C. No connectors pro- 
vided, see below. 



•( 1 



ElA/RS-232 connec- 
tor Part No DB25P 
$6 00 with 9. 8 con- 
ductor cable $19 65 
Part No DB25P9 



3' ribbon cable with at- 
tached connectors to fit 
TRS-BO and our serial 
board $3710 Part No 
3CAB40 



VIDEO TERMINAL 



m 



1 6 lines. 64 columns • 
Upper and lower case 

• 5x7 dot matrix • Se- 
rial RS-232 in and out 
with TTL parallel 
keyboard input • On 
board baud rate 
generator 75. 110, 
150, 300. 600. & 
12QQ \umper select- 
able • Memory 1024 
characters (7-21 L02J 

• Video processor chip 
SFF96364 by Necu- 
lonic • Control char- 
acters (CR. LF, -*, «-, 
T , i. non destructive 
cursor. CS, home. CL 

• White characters on 
black background or 
vice-versa • With the 
addition of a key- 
board, video monitor 
or TV set with TV 
interface (part no. 
107A) and power 
supply this is a com- 
plete stand alone 
terminal • also S-100 
compatible • requires 
+ 16. & -16 VDC at 
100mA. and 8VDC at 
1A. Part No. 1000A 

$296.45 kit. 



GAME PADDLES 

& SOUND 

FOR TRS-80 



Includes: 2 game pad- 
dles, interface, soft- 
ware, speaker, power 
supply, full documen- 
tation including: sche- 
matics, theory of 
operation, and user 
guide; plus 2 games on 
cassette, Pong and 
Starship War $157.29 
Complete Part No. 
7922C 



SERIAL/ 

PARALLEL 

INTERFACE 



• Converts serial to 
parallel and parallel to 
serial • Low cost on 
board baud rate gener- 
ator • 110to19.2K • 
Low power drain +5 
volts and -12 volts 
required • TTL com- 
patible • All characters 
contain a start bit, 5 
to 8 data bits, 1 or 2 
stop bits, and either 
odd or even parity. • All 
connections go to a 44 
pin gold plated edge 
connector • Board only 
$11.95 Part No. 101, 
with parts $42.89 Part 
No. 1 01 A. 44 pin edge 
connector $4.00 Part 
No. 44P 



MODEM 



• Type 103 •Full or half 
duplex • Works up to 
300 baud • Originate 
or Answer • Serial TTL 
input and output • con- 
nect 8 il speaker and 
crystal mic. directly to 
board • Requires +5 
volts • Board only $7.60 
Part No. 1 09. with parts 
$29.95 Part No. 109A. 



■V:<K 



OPTO-ISOLATED PARALLEL INPUT 
BOARD FOR APPLE II 

There are 8 inputs that 
can be driven from 
TTL logic or any 5 volt 
source. The circuit 
board can be plugged 
into any of the 8 sockets 
of your Apple II. It has 
a 16 pin socket for 
standard dip ribbon 
cable connection. 
Board only $15.65 
Part No. 1 20, with parts $69.95. Part No 1 20A 



iiiiiiiiiiiiiiiiiiiiiiiii 



SUPER MODEM 

Originate. RS-232 and 
20 mA compatable. Full 
mr duplex, and half duplex, 
^vj direct connect or a- 
M coustic coupled, on 
y ...iiflH board power supply.car- 

ner detect light, DB25 plug. 300 BAUD. Type 
103 compatable frequencies. Bare board Part 
No. 2000 $21 .89, Kit Part No. 2000A $1 33.80 



8K EPROM SAVER 






© • 



• Programs 2708's address relocation of each 
4K of memory to any 4K boundary • Power on 
jump and reset jump option for "turnkey" 
systems and computers without a front panel 

• Program saver software in 1 2708 EPROM 
$25. Bare board $45.59 including custom coil, 
board with parts but no EPROMS $1 64.69. 



APPLE II 
SERIAL I/O 
INTERFACE 



b2?TWMHM&&* 






Baud rate is continuously adjustable from 
to 30.000 • Plugs into any peripheral 
connector • Low current drain. RS-232 input 
and output • On board switch selectable 5 to 
8 data bits, 1 or 2 stop bits, and parity or no 
parity either odd or even • Jumper selectable 
address • SOFTWARE • Input and Output 
routine from monitor or BASIC to teletype or 
other serial printer • Program for using an 
Apple II for a video or an intelligent terminal. 
Also can output in correspondence code to 
interface with some selectrics. • Also 
watches DTR • Board only $14.95 Part No. 
2, with parts $51.25 Part No. 2A, assembled 
$62.95 Part No. 2C 



hen \m 



PARALLEL 

TRIAC OUTPUT 

BOARD FOR 

APPLE II 

This board has 8 triacs capable of switching 
110 volt 6 amp loads (660 watts per channel) or a 
total of 5280 watts. Board only $1 5.65 Part No. 
210, with parts $1 1 9.95 Part No. 21 OA 



APPLE II 
PROTOTYPING 
HOBBY/CARD 

Part No. 7907 
$21.95 



TAPE 
INTERFACE 



RS-232 20mA 
INTERFACE 

This board has two 
passive, opto-isola- 
ted circuits. One con- 
verts RS-232 to 
20mA, the other con- 
verts 20mA to RS- 
232. All connections 
go to a 10 pin edge 
connector. Requires 
+12 and -12 volts. 
Board only $9.95, 
part no. 7901. with 
parts $14.95 Part 
No. 7901A. 



TV. INTERFACE 



.^•ti 






• Converts a low cost 
tape recorder to a 
digital recorder • Works 
up to 1200 baud •Dig- 
ital in and out are TTL- 
serial • Output of 
board connects to mic. 
in of recorder • Ear- 
phone of recorder con- 
nects to input on board 

• No coils • Requires 
+5 volts, low power 
drain • Board only 
$7.60 Part No. 111. 
with parts $29. 95Part 
No. 111A 



MM*! 



• Converts video to 
AM modulated RF. 
Channels 2 or 3. So 
powerful almost no 
tuning is required. On 
board regulated power 
supply makes this ex- 
tremely stable. Rated 
very highly in Doctor 
Dobbs' Journal. Recom- 
mended by Apple • 
Power required is 12 
volts AC C.T.. or +5 
volts DC • Board only 
$8.19 part No. 107. 
with parts $18.85 Part 
No. 107A 



RS-232/TTL 
INTERFACE 



• Converts TTL to RS- 
232, and converts RS- 
232 to TTL • Two se- 
parate circuits • Re- 
quires -12 and +12 
volts • All connections 
go to a 10 pin edge 
connector, kit $9.95 Part 
No. 232A 1 0Pinedge con- 
nector $3.00 part No. 
10P. 



S-100 BUS ACTIVE TERMINATOR 



Board only $18.1 5 Part No. 900, with parts 
$29.89 Part No. 900A. 



SERIAL I/O 



Four Serial I/O RS-232 
ports. S-100 Bus, Soft- 
ware or jumper selectable 
baud rate (1 10, 300, 600, 
1 200. 2400, 4800, 9600, 
19.2K), on board Xtal baud 
rate generator, Address- 
ing, switch selectable, 
Parity or no panty (odd or 
even) switch selectable, 1 
or 2 stop bits, 5 to 8 
bits/character. Board only 
$35.19 Part No. 7908. 
With parts (kit) $199.95, 
Part No. 7908A. 



RS-232/TTY 
INTERFACE 



e . 






t>A*T *e goo 



This board has two 
active circuits, one con- 
verts RS-232 to 20 mA. 
the other converts 20 
mA to RS-232. Re- 
quires +12 and -12 
volts. $9.95 Part No. 
600A Kit. 



Send for FREE catalog ... a big self-addressed envelope with 86$ postage gets it fastest! 



TO 0rd6r ■ Mention P art no - description, and price. In USA shipping paid by us for orders accompanied by check or money 
order. We accept C.O.D. orders (U.S. only) or a VISA or Master Charge no., expiration date, signature and phone 
no., shipping charges will be added. CA residents add 6.5°/o for tax. Outside USA add 1 5°/o for air mail postage 
and handling. Payment must be in U.S. dollars. Dealer inquiries invited. Prices subject to change without notice. 



ORDER LINE: (408) 226-4064 



ELECTRONIC SYSTEMS ' 



KB, P.O. Box 18220, San Jose, CA USA 95158 



^47 



t^See List of Advertisers or) page 194 



Microcomputing, August 1981 177 



/I 



National 
Semiconductor 



Clock Modules 

12V DC 

AUTOMOTIVE/ 

INSTRUMENT 

CLOCK 

APPLICATIONS: 

• In-dash autoclocks 

• After market auto/ 
RV clocks 

• Aircraft-marina clk». 

• 12VOC opar. Inttru. 

• Portabla/battary 
powered instrumnts. 

Features: Bright 0.3" green display. Internal crystal time- 
base, t 0.5 sec. /day accur. Auto. display brightness control 
logic. Display color filterable to blue, blue-green, green & 
yellow. Complete -just add switches and lens. 

MA1003 Module $16.95 




MA1023 .7' 
MA1026 .7' 
MA 5036 3' 
MA1002 5' 

102 P20 
102 P22 
102 P20 



CLOCK MODULES 

Low Cost Digital LED Clock Module 8.95 
Dig. LED Alarm Clock/Thermometer 18.95 

Low Cost Digital LED Clock/Timer 6.95 

LED Display Dig. Clock & Xformer 9.95 

TRANSFORMERS 

Xformer for MAI 023 Clock Modules 3.49 

Xformer for MA1 026 Clock Modules 3.49 

Xformer for M A5036 Clock Modules 3.49 



MICROPROCESSOR COMPONENTS 



8080A/8080A SUPPORT DEVICES 

INStOtOA CPU 

DPSJ12 (-Bit Input/Output 

DPS214 Priority Interrupt Control 

DPUli Bl-Dlrectlonel Bui Driver 

DPS224 Clock Generator/Driver 

DPS22* But Driver 

DPS22* SyMem Controller/Bus Driver 

DPS23S Syrtem Controller 

INSS241 I/O Expander lor 41 Series 

INSS2S0 Asynchronous Comm. Element 

DP*»1 Proa. Comm. I/O IUSART) 

UPS2SJ Prog. Interval Timer 

DPS2U Prog. Peripheral I/O (PPI) 

DPS27 Pro*. DMA Control 

OPS2M Prog. Interrupt Control 

OPS27S Prog. CRT Controller 

DPttn Prog. Keyooaro/Dlsplay Interfece 

DPM00 Octal Bus Receiver 

DPUTU System Timing Element 

DPUM I-Blt Bi Directional Receiver 

DP1X7 t-BIt Bi Directional Receiver 

DPS30I S-BIt Bi Directional Receiver 



6 50 

3.2S 

S.K 

3*9 

3.« 

14* 

4.S* 

4 95 

995 

16.94 

7.tS 

14. 9i 

9.95 

It. 96 

14.9S 

49 95 

19.96 

*95 

6.95 

3.95 

3.96 

3.16 



6800/6800 SUPPORT DEVICES 




8 OHM SPEAKER 

2 1 /4" - 8 Ohm - .25 watt 
$1.25 ea. 2/$1.95ea. 10/$7.95ea. 



A0201 




H -801 159 



BATTERY HOLDER 

• Holds 2 ea. C cells 

• Aluminum Case 

• 5" leads 

$.45 each 10/S3.95 



MCMOO MPU 14.95 

MCM02CP MPU with Clock and RAM 19.96 

MC6I10API 12(*( Static RAM 4.95 

MC6I21 Peripheral Inter. Adapt (MC6S20) 7.49 

MC6S26 Priority Interrupt Controller 10.96 

MC6630LS 1024»( Bit ROM (MCMA30-I) 14.95 

MCfctSO Asynchronous Comm. Adapter 6.95 

MC6BV2 Synchronous Serial Data Adapter 6.96 

MC6660 0400bps Digital MODEM 10.95 

MC6K2 2400bps Modulator 12.96 

MC6M0A Quad 3-Stata Bus. Trans. (MCIT26) 2.25 

MICROPROCESSOR CHIPS 

2(0 (76T>C) CPU IMK36WN) (2MHI) 

ZMA (7*0-1 ) CPU (MK3M0N-4) (4MH*) 

CDPU02 CPU 

2650 MPU 

I DM2901 ADC CPU— 4-Bit Slice (Com. Temp. Grade) 



DATA ACQUISITION (CONTINUED)- 



ADC0609CCN 6 Bit A/D Converter (»-Ch. Multl.) 

ADC0917CCN • Bit A/D Converter (It-Ch. Multl.) 

O AC 1000LCN 10-Blt D/A Conv. Micro. Comp. (0.06%) 

OACIOOSUCN 10-Blt D/A Conv. Micro. Comp. (0.20%) 

DAC1020LCN 10-Blt D/A Converter (0X6% Lin.) 

OAC1022LCN 10-Blt D/A Converter (0.20% Lin.) 

DAC1222LCN 12-BltD/A Converter (0.20% Lin.) 

CD4051N l-Channei Multiplexer 

AV 51013 30K BAUD UART 

RAM'S 



5.2* 
10.96 
1396 
(.99 
(.49 
5.' 
9.9* 
1.19 
5.9* 



1101 2*6x1 Static 

1103 1024x1 Dynamic 

2101 ((101) 256x4 Static 

2102 1024x1 Static 
21L02 1024x1 Static 

2111 ((HI) 2*6x4 Static 

2112 296x4 Static MOS 
2114 1024x4 Static 460ns 
2114L 1024x4 Static 460ns Low Power 
2114-3 1024x4 Static 300ns 
2114L-3 1024x4 Static 300ns Low Power 
2117 16.3*4x1 Dynamic 560ns (housemarked 



4U6N-4(UPD41() 16K Dynamic 250ns (MM5290M-4) 

4164 64K Dynamic 250ns 

MM2147J 4096x1 Fast 70ns 

5101 2*6x4 Static 

MM5261 1024x1 Dynamic Fully Decoded 

MM5262 2Kxl Dynamic 

MM52M/2107 4096x1 Dynamic 

MM5290N-2 (4116) 16K Dynamic 150ns (UPD416C-3) 



MM529SJ-3A 

MM5799NAA/N 

UPO414/MK4027 

TMS4044-46NL 

TMS4045 



3.95 
1.7* 
1.9* 
3.95 
4.9* 
5.9* 
6.96 
7.49 
7.96 
) 4 95 
3.95 
49.95 
19.95 
7.9* 
.99 
.2* 
4.9* 
5.25 
4.9* 
9.95 
4.9* 
14.9* 
14.95 



r\- 



^i 



o 



82721 



BATTERY 
■ . HOLDER 

y* • Holds 4 ea. C cells 

• Plastic case 

• 9" leads 
$.49 ea 10/54.25 



EPROM Erasing Lamp 




1 


uaiaa 
1 - ■ ■ 


S 



13.95 
15.95 
19.95 
16.95 
19.95 
11.95 
16.95 
19.95 
24.95 
24.95 
29.96 
19.96 
29.96 
49.95 



MCS6502 MPU w/Clock (66K Bytes Memory) 

INSaOftN-6 MPU » Bit (6MH/| 

INSM39N-6 CPU Sgl. Chip (-Bit (12*Dytes RAM) 

INS(040N4 CPU (256 Bytes RAM) 

INS0070N CPU— (4 Bytes RAM 

INS9073N CPU W/Baslc Micro Interpreter 

Pt0*5 CPU 

INS0900 CPU-16-Blt 

TMS9900JL MPU-M-BIt 

SHIFT REGISTERS 

MM500H Dual 25-Blt Dynamic .50 

MM503H Dual 50-Blt Dynamic .50 

MM506H Dual 100-Bit Static .50 

MM510H Dual 64-Blt Accumulator .50 

MM1402 756 Bit Dynamic 3.95 

MM5013 1024-Bit Dynamic/Accumulator 1.95 

MM5016H 500/512-Bit Dynamic .(9 

MM5034N Octal (0-Bit 9.95 

MM5035N Octal (0-Blt 9.96 

2S0(V(14O4A) 1024 Bit Dynamic 3.95 

25KN Hex 32 Bit Static 4.95 

2522V Dual 132-Bit Static 2.96 

2524V 512 Bit Dynamic .99 

2525V 1024 Bit Dynamic 2.95 

2527V Dual 256-Bit Static 2.95 

2521V Dual 250-Bit Static 4.00 

2529V Dual 240-Bit Static 4.00 

2532N Quad (0-Bit Static 2.95 

3341PC Filo (Dual (0) 6.95 



• Erases 2708. 2716, 1702A, 5203Q. 5204Q. ate. 

• Erasas up to 4 chips within 20 minutes. 

• Maintains constant exposure distance of on* inch. 

• Special conductive foam liner eliminates static build-up. 

• Built-in safety lock to prevent UV exposure. 

• Compact - only 7-5/8" x 2-7/8" x 2" 

• Complete with holding tray for 4 chips. 

UVS-11E $79.95 



JOYSTICKS 



JS-6K 




JS-5K 5K Linear Taper Pots . 

JS 100K 100K Linear Taper Pots 
JVC 40 40K (2) Video Controller in case 




6-Digit 
Clock Kit 




• Bright .300 ht. comm. cath- 
ode display 

• Uses MM5314 clock chip 

• Switches for hours, minutes 
and hold modes 

• Hrs. easily viewable to 20 ft. 

• Simulated walnut case 

• 115 VAC operation 

• 12 or 24 hr. operation 

• Incl. all components, case & 
wall transformer 

• Size: 6%" x 3-1/8" x 1 V 



AF100-1CN 

AF121-1CJ 

AF122-1CJ 

LMMAH 

LM3J4/ 

LM335Z 

LF366N 

LF396N 

LM399H 

ADC0H4LCN 

DAC0606LCN 



DATA ACQUISITION 

Universal Active Filter 2.5% 5.95 

Touch Tone Low Pass Filter 19.96 

Touch Tone Low Pass Filter 19.95 

Super Gain Op Amp 1.00 

Constant Current Source 1.30 

Temperature Transducer 1.40 

JFET Input Op Amp 1.10 

Sample & Hold Amplifiers 3.95 

Temp. Comp. Prec. Ret. (.Sppm/C*) 4.95 

(-Bit A/D Converter (1 LSB) 4.95 

(-Bit D/A Converter (0.71% Lin.) 2.25 



1702 A 

270* 

TMS2716 

2716lntel(2516)TI 

2732lntel(2*32)TI 

275* 

5203 

S2S23(74S1(() 

S2SU5 

(2S123(74S2M) 

(2S165 



2513(2140) 
2513(3021) 
2516N 
MMS230N 



(K Dyn. 200ns (lower vt of MM5290J) 
Controller Oriented Processor 
4K Dynamic 16-pin 
4K static 
1024x4 Static 

- P ROMS/EP ROMS 

2K UV Erasable PROM 5.95 

(K EPROM 5.95 

16K EPROM (-6V, »SV, ♦ 12V) 19.96 

16K EPROM (Single +SV) 10.95 

32K EPROM 19.96 

(K EPROM (460ns) (Single «5V) 7.96 

20*4 PROM 14.(6 

32x( PROM (Open Collector) 4.(6 

4096 Bipolar PROM 19.96 

32x( Trl State Bipolar PROM 4.9* 

SK PROM 29.9* 

ROM'S 

Character Qeneretor (upper Case) 9.95 

Character Generator (Lower Case) 9.9* 

Character Generator 10.95 

20M-BII Read Only Memory 1.96 



-NMOS READ ONLY MEMORIES" 



MCM66710P 
MCM66740P 
MCM66750P 



12(x9x7 ASCII Shifted w/Greek 13.50 

12*x9x7 Math Symbol 4 Pictures 13.50 

12*x9x7 Alpha. Control Char. Gen. 13.50 



M-ZM 

M-CDPK02 

M-2650 



DS0025CN 

DS0O26CN 

INS1771N-1 

INS26S1N 

MM5(167N 

MM5(174N 

COP402N 

COP402MN 

COP470N 



MICROPROCESSOR MANUALS 

User Manual 750 

User Manual 7.50 

User Manual 5.00 

SPECIAL FUNCTION 

Dual MOS Clock Driver (SMZ) 3.50 

Dual MOS Clock Driver (SMZ) 1.96 

Floppy Disc Controller 24.96 

Communication Chip 19.96 

Microprocessor Real Time Clock (.96 

Microprocessor Compatible Clock 11.96 

Microcontroller with 64-Dlgit RAM 6.96 

and Direct LED Drive 

Microcontroller with 64-Dlgit RAM 7.49 

A Direct LED Drive w/N Buss Int. 

32 Seg. VAC Fluor. Driver (20-pln pkg.) 3.2* 



■TELEPHONE/KEYBOARD CHIPS 



AV-5-9100 
A V -5-9200 
AV-S-9500 
A V -5-2376 
HD0 1*5-5 
74C922 
74C923 
MM53190N 
MM57499N 



Push Button Telephone Dialer 
Repertory Dialer 
CMOS Clock Generetor 
Keyboard Encoder (U keys) 
Keyboerd Encoder (16 keys) 
Keyboard Encoder (16 keys) 
Keyboerd Encoder (20 keys) 
Push Button Pulse Dialer 



14.95 
14.95 
4.96 
11.96 
7.96 
5.49 
6.75 
7.96 



96/144 Key Serial Keyboerd Encoder (.95 






ELECTRONIC TOY MOTORS 






III 


Operating 

VoKeee 

Rene* 


TYPICAL CHARACTERISTICS 




SMALL 
TORQUE 




NO LOAD 


AT MAXIMUM EFMCIE WCV 


Voiteee 


Speed 


Current 


Speed 


Current 


Torque 


Output 


Eft 


RPM 


AMP 


RPM 


AMP 


at in 


m 


% 


02 IN 


DRV CELL 


1 5 6 


30 


9.200 


20 


6.750 


90 


260 


1 30 


57 


097 



.937 O.D. X 
1.201 Length 



MABUCHI RE280 $.99 each . . .10/$7.50. . .100/$50.00 



EXPERiMENTOR 
SOCKETS 



JE701 $19.95 




NEW 



JE215 Adjustable 
Dual Power Supply 

General Description: The JE215 is a Dual Power 
Supply with independent adjustable positive and nega- 
tive output voltages. A separate adjustment for each 
of the supplies provides the user unlimited applications 
for IC current voltage requirements. The supply can 
also be used as a general all-purpose variable power 

Supply. FEATURES 

• Adjustable regulated power supplies, 
pos. and nag. 1.2VDC to 15VDC. 

• Power Output (each supply): 

^£> * 5VDC 0? 500mA, 10V DC® 750mA, 

A 12VDC@ 500mA, and 

e» > 15VDC@> 175mA. 

• Two, 3 terminal adj. IC regulators 
' teefl with thermal overload protection. 

• Heat sink regulator cooling 

• LED "on" indicator 

• Printed Board Construction 

• 120VAC input 

• Size: 3 1/2"w x 5-1/16"L x 2"H 

JE21 5 Adj. Dual Power Supply Kit (as shown) . . $24.95 

(Picture not shown but similar in construction to above) 

JE200 Reg. Power Supply Kit (5VDC, 1 amp) . . $14.95 

JE205 Adapter Brd (toJE200) -5. -9 8. ±12V. $12.95 

JE210 Var Pwr. Sply. Kit, 5 15VDC. to 1 5amp. $19.95 




Stripe Price 

4(160) $ 4.7S 



94(470) 



EXP325 


1.8" 


2.1" 


.3" 


22(110) 


2(20) 


S 3 50 


EXP350 


3.6" 


2.1" 


.3" 


46(230) 


2(40) 


$ 6.75 


EXP600 


6.0" 


2.4" 


.6" 


94(470) 


2(80) 


$14.75 


EXP6S0 


3.6" 


2.4" 


.6" 


46(230) 


2(40) 


S 8.75 



Quick Test 
Sockets 
A Bus Strips 



QT I2S 



UT8S 



ot;s 





Lenetn 


How 
to hole 


Term, 
neh 


Unit 

r>..e. • 


OTMS 


65" 

65" 

S3" 

S3" 

4 1 

4.1" 


U" 


111 


(I1.M 


QT591 


62" 
5 0" 
50 
31 
3(" 


20 


$ m 


0T47S 


94 


% *.rt 


QT47I 
QT 1SS 


16 
70 


( l.M 
( 7 H 


QT JH 


12 


( 2 20 


QT IIS 


2 4" 


21" 


36 


( 4 64 


0T12S 

OTIS 

QT7S 


II- 
14" 
13" 


IS" 
1 1" 
1 0" 


24 
IE 
14 


( 3 76 
t 3 00 
( 2 7» 



$10.00 Min. Order - U.S. Funds Only 
Calif. Residents Add 6% Sales Tax 
Postage -Add 5% plus $1 Insurance 



Spec Sheets - 25«i 
^41 Sand 52(j Postage for your 

FREE 1981 JAMECO CATALOG 




ameco 



ELECTRONICS 



PHONE 

ORDERS 

WELCOME 

(415) 592-8097 



8/81 



MAIL ORDER ELECTRONICS - WORLDWIDE 

1355 SHOREWAY ROAD, BELMONT, CA 94002 

PRICES SUBJECT TO CHANGE 



1-9 


842-812 

10 99 


100 


.35 
1-9 


.30 

362-812 

10-99 


.25 
100 


.39 
1-9 


.35 

473-862 

10-99 


.30 
100 


.45 
1-9 


.39 

468-828 

10-99 


.35 
100 


.49 
1-9 


.45 

435-802 

10-99 


.39 
100 


.59 


.55 


.49 



POWER CORD SALE 

4>„ > _ 





il fi eaa* itvi . em 



AC and DC Wall Transformers 



Meet ter mm «*1N decks 
■(met. poewr uiepliei er 
iny other type of AC er 
DC iPplKeTion 




Part No. 



AC 250 
AC 500 
AC1000 
AC1700 
DV 9200 
DC 900 



Input 



117V/60H* 
117V/60Hz 
117V/60H2 
117V/60H2 
117V/60Hz 
120V/60H2 



Jutput 



12 VAC 250mA 

12 VAC 500mA 

12 VAC 1 amp 

9 VAC 1.7 amp 

9 VDC 200mA 

9 VDC 500mA 



Price 
$3.95 
$4.95 
$5.95 
$6 95 
$3.25 
$3.95 



CONNECTORS 




DB25P D Subminiature Plug «S2.95 

DB25S D Subminiature Socket $3.50 

DB51226 Cover for DB25P/S $1.75 

22/44SE P.C. Edge (22/44 Pin) $2.95 

UG88/U BNC Plug $1.79 

UG89/U BNC Jack $3.79 

UG175/U UHF Adapter $ .49 

S0239 UHF Panel Recp $1-29 

PL258 UHF Adapter $1.60 

PL259 UHF Plug $1.60 

UG260/U BNC Plug $1.79 

UG1094/U BNC Bulkhead Recp $1.29 

TRS-80 
16K Conversion Kit 

Expand your 4K TRS-80 System to 16K. 
Kit comes complete with: 

* 8 ea. MM5290 (UPD416/4116) 16K Dyn. Rami (*NS) 

* Documentation for Conversion 

TRS-16K2 -150NS $39.95 

TRS-16K4 «250ns $29.95 



JE610 ASCII 
Encoded Keyboard Kit 





The JE610 ASCII Keyboard Kit can be interfaced into 
most any computer system. The kit comas complete 
with an Industrial grade keyboard switch assembly 
(62 keys), IC's. sockets, connector, electronic compo- 
nents and a double-sided printed wiring boerd. The 
keyboard assembly requires +5V @ 150mA and -12V 
<a 10 mA for operation. Features: 60 keys generate the 
126 cheracters, upper and lower case ASCII set. Fully 
buffered. Two user-define keys provided for custom 
applications. Caps lock for upper-case-only alpha charac- 
ters. Utilizes a 2376 (40 pin) encoder read-only memory 
chip. Outputs directly compatible with TTL/DTL or 
MOS logic arrays. Easy interfecing with a 16 pin dip or 
18-pin edge connector. Size: 3>4"H x 14H"W x 8X"D 

JE610/PTE-AK . ( s A pVcVu a rea a a; t o:g) $124.95 

ircini/:* 62-Key Keyboard, PC Board. * -?q nc 
JlO IU MI I Components (no case) 9 /o.sO 

K62 62-Key Keyboard (Keyboard only) . . .$ 34.95 

DTE-AK (case only - 3*"Hxn"Wx8*"D)$ 49.95 

AAA/rWi JE212 - Negative 12VDC Adapter Board Kit 
£nEWK for JE610 ASCII KEYBOARD KIT Kit/ 

■Twvv^ Provides -12V DC from incoming5VDC . . $9.95 



JE600 
Hexadecimal Encoder Kit 



FULL 8 BIT- 
LATCHED OUTPUT 
19-KEY KEYBOARD 







The JE600 Encoder Keyboard Kit provides two separate 
hexadecimal digits produced from sequential key entries 
to allow direct progremming for 8-bit microprocessor 
or 8-bit memory circuits. Three additional keys ere pro- 
vided for user operations with one having a bistable 
output available. The outputs are latched end monitored 
with 9 LED readouts Also included Is a key entry strobe. 
Features: Full 8-bit latched output for microprocessor 
use. Three user-define keys with one being bistable 
operation. Debounce circuit provided for all 19 keys. 
9 LED readouts to verify entries. Easy interfacing with 
standard 16-pin IC connector. Only +5VDC required 
for operation. Size: 3'/i"H x 8'/«"VV x 8K"D 

JE600/DTEHK P&XS'SZZi $99.95 

,r Cnn tr:*. 19-Key Hexadec. Keyboard. «*.,-<, qc 
JcDOO Kit PC Board tCmpnts. (no case) . .fcOy.yO 

K19 19-Key Keyboard (Keyboard only) .... $14.95 
DTE-HK (case only -3Vi"Hx8V. ,, Wxt¥i' , D) $44.91^ 



178 Microcomputing, August 1981 



C ^Ki 



7400 






SN7400N 


.25 


SN7472N 


.29 


SN741S6N 


.79 


SN7401N 


.20 


SN7473N 


35 


SN741S7N 


.69 


SN7402N 


.25 


SN7474N 


.35 


SN74160N 


.89 


SN7403N 


.25 


SN7475N 


.49 


SN74161N 


89 


SN7404N 


.25 


SN7476N 


.35 


SN74162N 


.89 


5N7406N 


.29 


SN7479N 


5.00 


SN74163N 


.89 


SN7405N 


.35 


SN7480N 


.50 


SN74164N 


.89 


SN7407N 


.36 


SN7482N 


.99 


SN74166N 


.89 


SN7408N 


.29 


SN7483N 


.69 


SN74166N 


1.25 


SN7409N 


.29 


SN7486N 


.89 


SN74167N 


2.79 


SN7410N 


.25 


SN7486N 


.35 


SN74170N 


1.95 


SN7411N 


.29 


SN7489N 


1.75 


SN74172N 


4.95 


SN7412N 


.35 


SN7490N 


.49 


SN74173N 


1.39 


SN7413N 


.40 


SN7491N 


.59 


SN74174N 


.99 


SN7414N 


.69 


SN7492N 


.45 


SN74175N 


.89 


SN7416N 


.29 


SN7493N 


.45 


SN74176N 


.79 


SN7417N 


.29 


SN7494N 


.69 


SN74177N 


.79 


SN7420N 


.25 


SN7496N 


.69 


SN74179N 


1.49 


SN7421N 


.29 


SN7496N 


.69 


SN74180N 


.79 


SN7422N 


.45 


SN7497N 


3.00 


SN74181N 


2.25 


SN7423N 


.29 


SN74100N 


1.49 


SN741S2N 


.79 


SN7425N 


.29 


SN74104 


.89 


SN74184N 


2.49 


SN7426N 


.29 


SN74105 


.89 


SN74186N 


2.49 


SN7427N 


.25 


SN74107N 


.35 


SN74190N 


1.25 


SN7428N 


.49 


SN74109N 


.39 


SN74191N 


1.25 


SN7430N 


.25 


SN74116N 


1.95 


SN74192N 


.89 


SN7432N 


.29 


SN74121N 


.39 


SN74193N 


.89 


SN7437N 


.25 


SN74122N 


.55 


SN74194N 


.89 


SN7438N 


.40 


SN74123N 


.59 


SN74195N 


.69 


SN7439N 


.25 


SN74125N 


.49 


SN74196N 


.89 


SN7440N 


.20 


SN74126N 


.49 


SN74197N 


.89 


SN7441N 


.19 


SN74132N 


.75 


SN74198N 


1.49 


SN7442N 


.59 


SN74136N 


.75 


SN74199N 


1.49 


SN7443N 


1.10 


SN 74141 N 


.99 


SN 74221 N 


1.25 


SN7444N 


1.10 


SN74142N 


3.25 


SN 74251 N 


.99 


SN7445N 


89 


SN74143N 


3.49 


SN74276N 


1.95 


SN7446N 


.79 


SN74144N 


3.49 


SN74279N 


.79 


SN7447N 


.69 


SN74145N 


.79 


SN74283N 


1.49 


SN7448N 


.79 


SN74147N 


1.95 


SN74284N 


3.95 


SN7450N 


.20 


SN74148N 


1.29 


SN74285N 


3.95 


SN7451N 


.20 


SN741S0N 


1.25 


SN74365N 


.69 


SN74S3N 


.20 


SN 74151 N 


.69 


SN74366N 


.69 


SN7454N 


.20 


SN74152N 


.69 


SN74367N 


.69 


SN74S9A 


.25 


SN741S3N 


.79 


SN74368N 


.69 


SN7460N 


.20 


SN74154N 


1.25 


SN74390N 


1.49 


SN7470N 


.29 


SN74155N 


.79 


SN74393N 


1.49 


74LS00 
74LS01 


.29 
.29 


74LS 


74LS192 
74LS193 


1.15 
1.15 


74LS02 


.29 


74LS92 


.75 


74LS194 


1.15 


74LS03 


29 


74LS93 


.75 


74LS19S 


1.15 


74LS04 


.35 


74LS96 


.99 


74LS197 


1.19 


74LS05 


.35 


74LS96 


1.15 


74LS221 


1.19 


74LS06 


.29 


74LS107 


.45 


74LS240 


1.95 


74L.S09 


.36 


74LS109 


.45 


74LS241 


1.95 


74LS10 


.29 


74LS112 


.45 


74LS242 


1.95 


74LS11 


.75 


74LS113 


.49 


74LS243 


1.95 


74LS12 


.35 


74 LSI 14 


.49 


74LS244 


1.95 


74 US 13 


.59 


74LS122 


.89 


74LS245 


2.95 


74LS14 


.99 


74LS123 


1.25 


74LS247 


1.19 


74LS15 


.35 


74LS125 


.89 


74LS248 


1.19 


74LS20 


.29 


74LS126 


.55 


74LS249 


1.19 


74LS21 


.35 


74LS132 


.99 


74LS251 


1.49 


74LS22 


.35 


74LS133 


.89 


74LS253 


.99 


74LS26 


.35 


74LS136 


.49 


74LS257 


.89 


74LS27 


.35 


74LS138 


.89 


74LS2S8 


.99 


74L.S28 


.35 


74LS139 


:H 


74LS260 


.69 


74LS30 


.29 


74LS151 


74LS266 


.69 


74LS32 


.35 


74LS153 


.89 


74LS273 


1.95 


74LS33 


.59 


74L.S154 


1.75 


74LS279 


.75 


74LS37 


.45 


74LS155 


1.19 


74LS283 


1.09 


74LS38 


.49 


74LS156 


1.19 


74LS290 


.99 


74LS40 


.35 


74LS157 


.89 


74LS293 


.99 


74LS42 


.19 


74LS158 


.99 


74LS29S 


1.25 


74LS47 


.19 


74LS160 


1.15 


74LS352 
74LS353 


1.29 


74LS48 


1.15 


74LS161 


1.15 
1.15 


1.29 


74LS49 


1.15 


74LS162 


74LS365 


.75 


74LS51 


.29 


74LS163 


1.15 


74LS366 


.75 


74LS54 


.29 


74LS164 


1.25 


74LS367 


.78 


74LS55 


.29 


74LS165 


1.25 


74LS368 


.75 


74LS73 


.45 


74LS168 


1.19 


74LS373 


1.95 


74LS74 


.45 


74LS169 


1.19 


74LS374 


1.95 


74LS75 


59 


74LS170 


2.49 


74LS375 


.89 


74LS76 


.45 


74LS173 


1.39 


74LS386 


.69 


74LS78 


.49 


74 LSI 74 


.99 


74LS393 


2.49 


74LS83 


.89 


74LS175 


.99 


74LS399 


2.49 


74LS85 


1.25 


74LS181 


2.95 


74LS670 


2.49 


74LS86 


.45 


74LS190 


1.25 


81LS9S 


1.95 


74LS90 


.59 


74LS191 


1.25 


81 LS97 


1.95 



74SOO 

74S02 

74503 

74S04 

74S06 

74S08 

74S09 

74S10 

74S11 

74S15 

74S20 

74S22 

74S30 

74S32 

74S38 

74S40 

74S51 

74S64 

74S65 

74S74 

74S86 

74S112 

74S113 

74S114 



.50 

.50 

.50 

.55 

.55 

.50 

.50 

.50 

.50 

.50 

.50 

.50 

.50 

.55 

.69 

.55 

.50 

.50 

.50 

.79 

.79 

.79 

.79 

.79 



7AS 



74S124 

74S133 

74S134 

74S135 

74S136 

74S13S 

74S139 

74S140 

74S151 

74S153 

74S157 

74S158 

74S160 

74S174 

74S175 

74S188 

74S194 

74S195 

74S196 

74S240 

74S241 

74S242 



2.49 
.55 
.69 
1.19 
1.75 
1.35 
1.35 
1.15 
1.35 
1.35 
1.35 
1.35 
1.95 
1.59 
1.59 
4.95 
1.95 
1.95 
195 
2.95 
2.95 
3.25 



74S243 

74S244 

74S251 

74S253 

74S257 

74S258 

74S260 

74S280 

74S287 

74S288 

74S373 

74S374 

74S387 

74S471 

74S472 

74S473 

74S474 

74S475 

74S570 

74S571 

74S572 

74S573 

74S940 

74S941 



3.25 

3.25 

1.45 

1.45 

1.35 

1.35 

.79 

2.95 

4.95 

4.95 

3.49 

3.49 

5.95 

19.95 

19.95 

19.95 

21.95 

21.95 

7.95 

7.95 

19.95 

19.95 

3.15 

3.15 



CA3010H 
CA3013H 
CA3023H 
CA3035H 
CA3039H 
CA3046N 
CA30S9N 



1.07 
2AS 
3.25 
2.48 
1.35 
1.30 
3.25 



CA-LINEAR 



CA3060N 
CA3080H 
CA3081N 
CA3062N 
CA3083N 
CA3086N 



3.25 
1.25 
2.00 
2.00 
1.60 
.85 



CA3089N 
CPOOKN 
CA3130H 
CA3140H 
CA3160H 
CA3401N 
CA3600N 



3.75 
3.95 
1.39 
1.25 
1.25 
.59 
3.50 



CO4000 


.39 






CD 4098 


2.49 


CD4001 


.39 


CD-CI 


CO4506 


.75 


CO4002 


.39 






CD4507 


.99 


CO4006 


1.19 


CO4041 


1.49 


CD4508 


3.95 


CD4007 


.25 


CO4042 


.99 


CO45i0 


1.39 


CD4009 


.49 


CD4043 


.89 


CD4511 


1.29 


CD4010 


.49 


CD4044 


.89 


CD4S12 


1.49 


CO4011 


.39 


C CM 046 


1.79 


CD4514 


3.95 


CD4012 


.25 


CO4047 


2.50 


CD4515 


2.95 


CO4013 


.49 


CO4048 


1.3S 


CD4S16 


1.49 


CD4014 


1.39 


CO4049 


.49 


CD4518 


1.79 


CD4015 


1.19 


CD4050 


.69 


CD4519 


.89 


CD4016 


.59 


CD4051 


1.19 


CD4520 


1.29 


CO4017 


1.19 


CD4052 


1.19 


C04526 


1.79 


CO4018 


.99 


CD4053 


1.19 


CD4528 


1.79 


CO4019 


.49 


CD4056 


2.95 


CD4529 


1.95 


CD4020 


1.19 


CD4059 


9.95 


CD4543 


2.79 


CO4021 


1.39 


CO4060 


1.49 


CD4562 


11.95 


CO4022 


1.19 


CD4066 


.79 


CD4566 


2.79 


CO4023 


.29 


CO4068 


.39 


CD4583 


2.49 


CD4024 


.79 


CO4069 


.45 


CD4584 


.75 


CD4025 


.23 


CO4070 


.55 


C04723 


1.95 


CO4026 


2.95 


CD4071 


.49 


C04724 


1.95 


CD4027 


.69 


CD4072 


.49 


MC14409 


14.95 


CD4028 


.89 


CO4073 


.39 


MC14410 


14.95 


CD4029 


1.49 


CD4075 


.39 


MC14411 


14.95 


CO4030 


.49 


CO4076 


1.39 


MC14412 


11.95 


CD4034 


3.49 


CO4078 


.55 


MC14419 


4.95 


CD4035 


.99 


CO4081 


.39 


MC 14433 


13.95 


CD4040 


1.49 


CO4082 


.39 


MC1453S 


2.49 


*s-— 


1 


CD4093 


.99 


MC14541 


1.95 




DIP/IC INSERTION TOOL 
WITH PIN STRAIGHTENER 





Vacuum Vise 

Vacuum based light-duty 
vise for small components!! 
end assemblies. ABS con 
struction. 1%" jaws, VA" ■ 
travel. Can be permanent- 
ly installed. 

VV-1 $3.49 



iH»ICM!l» PINS 



Inserts both 14 and 18 pin packages 
Narrow profile permits work on close- 
ly spaced items. Pin straightener built 
into handle. 



$349 
7.96 
7.96 
7.95 



INS 1416 14 16 pin 

MOS 1416 14 16 pin CMOS wfe 

MOS 2428 24 28 pin CMOS safe 

MOS 40 36 40 pin CMOS safe 




Wire Wrapping 
Kit WK-2 

Contains WSU-30 wrap tool, 50 
fatt of Kynar 30 AWG white 
wire, 50 pieces each prs-stripped 
wire in 1", 2" 3" and 4" lengths, 
stripped 1 " both ends. 

WK-2 $12.95 



DISCRETE LEDS 



XC556R .200" red 5/S1 

XC556G .200" green 4/$l 

XC556Y .200" yellow 4/J1 

XC556C .200" clear 4/J1 

XC22R .200" red 5/51 

XC22G .200" green 4/$l 

XC22Y .200" yellow 4/$l 

MV10B .170" red 4/$l 



MV50 

XC209R 

XC209G 

XC209Y 

XC526R 

XCS26G 

XC526Y 

XC526C 



.085" red 
.125" red 
.125" green 
.125" yellow 
.185" red 
.185" green 
185" yellow 
185" clear 



6/$l 
S/$l 
4/$l 
4/$l 
5/$l 
4/S1 
4/S1 
4/$l 



6 VOLT MINI LAMP 

- INCANDESCENT - 

600 147 Clear w/5" leads 8/$1 
80620 Red w/10" leads 9/$1 



XCIM DID LEO, METAL 
MTO. HOW. I-*'' LEADS. 

RL-2 . .$.39 ea. or 3/$1 .00 



C.A. — 

Type 

MAN 1 
MAN 2 
MAN 3 
MAN 52 
MAN 54 
MAN 71 
MAN 72 
MAN 74 
MAN 82 
MAN 84 
MAN 3620 
MAN 3630 
MAN 3640 
MAN 4610 
MAN 6610 
MAN 6630 
MAN 6640 
MAN 6650 
MAN 6660 
MAN 6710 
MAN 6750 
MAN 6780 
DLO304 
DL.O307 
DLG500 



Common Anode DISPLAY LEDS C -C - Common Cathode 



Polarity Ht Price 

C.A.— red .270 2.95 

5x7 O.M.— red .300 4.95 

CC— red .125 .25 

C A.— green .300 1.25 

CC— green .300 1.25 

C.A.— red .300 .75 

C.A.— red .300 .75 

CC— red .300 1.25 

C.A.— yellow .300 .49 

CC— yellow .300 .99 

C.A.— orange .300 .49 

C.A.— orange ± 1 .300 .99 

CC— orange .300 .99 

C.A. —orange .400 .99 

C.A.— orange— DD .560 .99 

C.A.— orange i 1 .560 .99 

CC— orange— DO .560 .99 

CC— orange ± 1 .560 .99 

C.A.— orange .560 .99 

C.A.— red— DD .560 .99 

CC— red ±1 .560 .99 

CC— red .560 .99 

CC— orange .300 1.25 

C.A. —orange .300 1.25 

CC— green .500 1.25 



Typ« 

DLG507 

DL704 

DL707 

DL728 

DL741 

DU746 

DL747 

DL750 

DLOS47 

DLO850 

DL33B 

FND35B 

FND359 

FND503 

FND507 

HDSP-3401 

HDSP-3403 

5082-7751 

5082-7760 

5082-7300 

5082-7302 

5082-7304 

4N28 

LIT-1 

MOC3010 



Polarity Ht 

C.A. —green .500 

CC— red .300 

C.A.— red .300 

CC— red .500 

C.A.— ted .600 

C.A.— red ± 1 .630 

C.A.— red .600 

CC— red .600 

C.A.— orange .600 

CC— orange .800 

CC— red .110 

CC ± 1 .357 

CC .357 

CC (FNDSOO) .500 

C.A. (FND510) .500 

C.A.— red .800 

CC— red .800 

C.A..R.H.D.— red .430 

C.C.R.H.D.— red .430 

4x7 sgl. dig. RHD .600 

4x7 sgl. dig. LHO .600 

Overnge. char. (± 1) .600 
Photo XsistorOpto-lsol. 
Photo Xsistor Opto-isoi. 
Optically Isol.Trlac Driver 1.25 



Price 

1.25 

1.25 

1.25 

1.49 

1.25 

1.49 

1.49 

1.49 

1.49 

1.49 

.35 

.99 

.75 

.99 

.99 

1.50 

1.50 

1.25 

1.75 

22.00 

22.00 

19.95 

.99 

.69 



SOCKETS 




* Nickel Boron Plating 
•G.F.PSF Plastic Body 

* For testing IC's 

Part No. Pins Price i Part No. Pins Price 

214-3339 14 pin 5.95 222-3343 22 pin 9.95 
216-3340 16 pin 6.49 224-3344 24 pin 9.75 
218-3341 18 pin 7.95 228-3345 28 pin 11.95 
220-3342 20 pin 8.95 | 240-3346 40 pin 12.95 



^^>w RECEPTACLES 

Test W* l *W Sockets j\ 

ZERO INSERTION FORCE 

* Nickel Boron Plating 
*G.F. PSF Plastic Body 

• Wire Wrap Contacts 
Part No . Pins Price i Part No. Pins Price 



r 



LOW PROFILE 
(TIN) SOCKETS 



1-24 



8 pin LP 
14 pin LP 
16 pin LP 
18 pin LP 
20 pin LP 
22 pin LP 
24 pin LP 
28 pin LP 
36 pin LP 
40 pin LP 



25-49 



50-100 



.17 
.20 
.22 
.29 
.34 
.37 
.38 
.45 
.60 
.63 



.16 
.19 
.21 
.28 
.32 
.36 
.37 
.44 
.59 
.62 



.15 
.18 
.20 
.27 
.30 
.35 
.36 
.43 
.58 
.61 



D 



214-3592 14 pin 9.75 222-3596 22 pin 12.95 

216-3593 16 pin 9.95 224-3597 24 pin 12.75 

218-3594 18 pin 10.95 228-3598 28 pin 13.95 

220-3595 20 pin 11.95 I 240-3599 40 pin 15.95 



TrrrnT 



SOLDERTAIL 
STANDARD (TIN) 



1-24 



25-49 



50-100 



atfsf 
TrrrTTr 



8 pin SG 
14 pin SG 
16 pin SG 
18 pin SG 
24 pin SG 
28 pin SG 
36 pin SG 
40 pin SG 



SOLDERTAIL (GOLD) 
STANDARD 



1-24 



25-49 



50-100 



.39 

.49 

.54 

.59 

.79 

1.10 

1.65 

1.75 



.35 

.45 

.49 

.53 

.75 

1.00 

1.40 

1.59 



.31 
.41 
.44 
.48 
.69 
.90 
1.26 
1.45 



14 pin ST 


.27 


.25 


16 pin ST 


.30 


.27 


18 pin ST 


.35 


.32 


24 pin ST 


.49 


.45 


28 pin ST 


.99 


.90 


36 pin ST 


1.39 


1.26 


40 pin ST 


1.59 


1.45 



.24 
.25 
.30 
.42 
.81 
1.15 
1.30 




WIRE WRAP SOCKETS 
(GOLD) LEVEL #3 



1-24 



25-49 



50-100 



8 pin 
10 pin 
14 pin 
16 pin 
18 pin 
20 pin 
22 pin 
24 pin 
28 pin 
36 pin 
40 pin 



WW 
WW 
WW 
WW 
WW 
WW 
WW 
WW 
WW 
WW 
WW 



.59 

.69 

.79 

.85 

.99 

1.19 

1.49 

1.39 

1.69 

2.19 

2.29 



.54 

.63 

.73 

.77 

.90 

1.08 

1.35 

1.26 

1.53 

1.99 

2.09 



.49 

.58 

.67 

.70 

.81 

.99 

1.23 

1.14 

1.38 

1.79 

1.89 



1/4 WATT RESISTOR ASSORTMENTS -5% 



:db. 



Part No. Function 

7046IPI CMOS Precision Timer 

7045EV/Kif Stopwatch Chip, XTL 

7106CPL 3Vi Digit A/D (LCD Drive) 

7106EV/Kif IC. Circuit Board. Display 

7107CPL 3W Digit A/D (LED Drive) 

7107EV/Kif IC, Circuit Board, Display 

7116CPL JW Digit A/D LCD DIs. HgtD 

7117CPL 3W Digit A/D LED DIs. HLD. 

7201IDR Low Battery Volt Indicator 

7205IPG CMOS LED Stopwatch/Timer 

7205EV/Klt* Stopwatch Chip, XTL 

7206CJPE Tone Generator 

720SCEV/KU* Tone Generator Chip, XTL 

7207AIPD Oscillator Controller 

7207AEV/KU* Freq. Counter Chip, XTL 

720JIPI Seven Decade Counter 

7209IPA Clock Generator 

7215IPG 4 Func. CMOS Stopwatch CKT 

7215EV/K!t* 4 Func. Stopwatch Chip, XTL 

7216AUI 8-Dlgit Univ. Counter C.A. 

7216CIJI 8-Dlgit Freq. Counter C.A. 

7216DIPI 8-Diglt Freq. Counter CC 

7217IJI 4-Olglt LED Up/Down Counter 

7218CIJI 8-Dlglt Univ. LED Drive 

7224IPL LCD 4W Digit Up Counter ORI 

7226AIJL 8-Digit Univ. Counter 

7226AEV/KU* 5 Function Counter Chip. XTL 

7240IJE CMOS Bin Prog. Timer/Counter 

7242UA CMOS Dlvlde-by-256 RC Timer 

7250IJE CMOS BCD Prog. Timer/Counter 

7260IJE CMOS BCD Prog. Timer/Counter 

7S66IPA CMOS 555 Timer (8 pin) 

7556IPD CMOS 556 Timer (14 pin) 

76UBCPA CMOS Op Amp Comparator 

7612BCPA CMOS Op Amp Ext. Cmvr. 

7621BCPA CMOS Dual Op Amp Comp. 

7631CCPE CMOS Trl Op Amp Comp. 

7641CCPO CMOS Quad Op Amp Comp. 

7642CCPD CMOS Quad Op Amp Comp. 

7660CPA Voltage Converter 

8038CCPD Waveform Generator 

8048CCPE Monolithic Logarithmic Amp 

8069CCQ SOppm Band— GAP Volt Ret. Diode 

8211CPA Volt Ref/lndlcator 

8212CPA Volt Ref/lndlcator 



Price 

14.96 

22.96 

16.98 

34.96 

15.96 

28.95 

18.96 

17.96 

2.25 

12.95 

19.96 

5.15 

9.95 

6.50 

11.10 

17.95 

3.95 

13.95 

19.96 

32.00 

26.96 

21.95 

12.95 

10.95 

11.25 

31.95 

74.95 

4.95 

2.05 

6.00 

6.25 

1.46 

2.20 

5MV 2.25 

5MV 2.95 

SMV 3.95 

10MV 5.35 

10MV 7.50 

10MV 7.50 

2.95 

4.95 

21.60 

2.50 

2.50 

2.50 



74C00 
74C02 
74C04 
74C06 
74C10 
74C14 
74C20 
74C30 
74C42 
74C48 
74C73 
74C74 
74C85 
74C86 
74C89 
74C90 
74C93 



.39 

.39 

.39 

.39 

.39 

.75 

.39 

.39 

1.39 

1.95 

.79 

.79 

1.95 

.99 

6.95 

1.29 

1.29 



74C 



74C95 

74C107 

74C151 

74C154 

74C157 

74C160 

74 C 161 

74C162 

74C163 

74C164 

74C173 

74C174 

74C175 

74C192 

74C193 

74C195 



1.59 
1.89 
2.95 
3.95 
2.25 
1.69 
1.60 
1.49 
1.69 
1.59 
1.39 
1.39 
1.39 
1.69 
1.69 
159 



74C221 

74C240 

74C244 

74C373 

74C374 

74C901 

74C903 

74C911 

74C912 

74C915 

74C917 

74C922 

74C923 

74C925 

74C926 

80C96 

80C97 



1.95 

2.25 

2.25 

2.49 

2.59 

.89 

1.15 

10.95 

10.96 

1.69 

10.96 

5.49 

5.75 

7.50 

7.50 

.79 

.79 



LH0002CN 6.85 
LM10CLH 4.50 
LM11CLH 4.75 
L HOC 70- OH 6.05 
TL071CP .79 

TL072CP 1.39 
TL074CN 2.49 
LH00B2CD 35.80 
TL082CP 1.19 
TL084CN 2.19 
LH0094CD 36.80 
LM300H .99 

LM301CN/H .35 
LM302H 1.95 

LM304H 1.95 

LM305H .99 

LM307CN/H .45 
LM30BCN/H 1.00 



LINEAR 



LM309H 

LM309K 

LM310CN 

LM311H/CN 

LM312H 

LM317MP 

LM317T 

LM317K 



1.95 
1.25 
1.75 
.90 
2.49 
1.15 
1.75 
3.95 



LM318CN/H 1.95 



LM319N 

LM320K-5 

LM320K-12 

LM320K-15 

LM320T-5 

LM320T-12 

LM320T-15 

LM323K-5 

LM324N 

LM329DZ 

LM331N 

LM334Z 

LM335Z 

LM336Z 

LM337T 

LM337MP 

LM338K 

LM339N 

LM340K-5 

LM340K-12 

LM340K-15 



1.95 
1.36 
1.35 
1.35 
1.25 
1.25 
1.25 
5.95 
.99 
.65 
3.95 
1.30 
1.40 
1.75 
1.95 
1.15 
6.95 
.99 
1.35 
1.35 
1.35 



LM340T-5 

LM340T-12 

LM340T-15 

LM341P-5 

LM341P-12 

LM341P-15 

LM342P-5 

LM342P-12 

LM342P-15 

LM34SN 

LM350K 

LF351N 

LF353N 

LF355N 

LF356N 

LM358N 

LM3S9N 

LM370N 

LM373N 

LM377N 

LM380N 

LM381N 

LM382N 

LM384N 

LM386N-3 

LM387N 

LM389N 

LM392N 

LF396N 

LM399H 

TL494CN 

TL496CP 

NE510A 

NE529A 

NE531H 

NE536H 

NE540H 

NE544N 

NE550A 

NE556V 

LM556N 

NE564N 

LM565N 

LM566CN 

LM567V 

NE570N 



1.25 
1.25 
1.25 
.75 
.75 
.75 
.69 
.69 
.69 
1.25 
5.75 
.60 
1.00 
1.10 
1.10 
1.00 
1.79 
4.49 
3.25 
2.95 
125 
1.95 
1.79 
1.95 
1.29 
1.45 
1.36 
.69 
4.00 
5.00 
4.49 
1.75 
6.00 
4.95 
3.95 
6.00 
6.00 
4.95 
1.30 
.39 
.99 
3.95 
1.25 
1.95 
1.25 
4.95 



LM702H 


.79 


LM703CN 


.89 


LM709N 


.49 


LM710N 


.79 


LM711N 


.79 


LM723N 


.69 


LM733N/H 


1.00 


LM739N 


1.19 


LM741CN 


.35 


MC1741SCG 


3.00 


LM747N/H 


.79 


LM748N/H 


.59 


LM1014N 


2.75 


LM1310N 


1.95 


LM14S8CN 


.59 


LM1488N 


1.25 


LM1489N 


1.25 


LM1496N 


1.95 


LM1556V 


1.75 


LM1800N 


2.96 


LM1877N4 


3.25 


LM1S89N 


3.20 


LM1896N 


1.75 


LM2002T 


1.49 


LM2877P 


2.05 


LM2878P 


2.25 


LM2896P-1 


2.25 


LM3189N 


2.95 


LM3900N 


.69 


LM3905CN 


1.25 


LM3909N 


1.15 


LM3914N 


3.95 


LM3915N 


3.95 


LM3916N 


3.95 


RC4136N 


1.25 


RC4151NB 


3.95 


RC4194TK 


5.95 


RC4195TK 


5.49 


KB4428 


4.25 


KB4429 


5.95 


LM4500A 


3.25 


ICL8038B 


4.95 


LM13080N 


1.29 


LM136O0N 


1.49 


75138N 


1.95 


75450 N 


.89 


75451CN 


.39 


75492 


.89 



ASST. 1 5ee. 



10 Ohm 12 Ohm 15 Ohm 18 Ohm 22 Ohm 
27 Ohm 33 Ohm 39 Ohm 47 Ohm 56 Ohm 



50 pes. $1.95 



ASST. 2 5ee. 



68 Ohm 82 Ohm 100 Ohm 120 Ohm 150 Ohm 
180 Ohm 220 Ohm 270 Ohm 330 Ohm 390 Ohm 



50pcs. $1.95 



ASST. 3 5ea. 



470 Ohm 560 Ohm 680 Ohm 820 Ohm IK 
1.2K 1.5K 1.8K 2.2K 2.7K 



50 pes. $1.95 



ASST. 4 5ea. 



3.3K 
8.2K 



3.9K 
10K 



4.7K 
12K 



5.6K 
15K 



6.8 K 
1SK 



ASST. 5 Sea. 



22K 

56K 



27K 
68K 



50 pes. $1.95 



33 K 
82K 



39K 

100K 



47K 

120K 



50 pes. $1.95 



ASST. 6 5ea. 



150K 
390 K 



180 K 
470K 



220 K 
560K 



270K 
680K 



330K 
820K 



50 pes. $1.95 



ASST. 7 5ea. 



1M 
2.7M 



1.2M 
3.3M 



l.SM 
3.9M 



l.SM 
4.7M 



2.2M 
5.6M 



ASST. 8R 



50 pes. $1.95 



Includes Resistor Assts. 17 (350 pes.) $10.95 ea. 



$10.00 Mm. Order - U.S. Funds Only 
Calif. Residents Add 6% Sales Tax 
Postage- Add 5% plusSI Insurance 



^41 





Spec Sheets - 25* 

Send 52 4 Postage for your 

FREE 1981 JAMECO CATALOG 

PHONE 

ORDERS 

WELCOME 

(415) 592-8097 



8/81 



ameco 



ELECTRONICS 



MAIL ORDER ELECTRONICS - WORLDWIDE 

1355 SHORE WAY ROAD, BELMONT, CA 94002 
PRICES SUBJECT TO CHANGE 



CAPACITOR CORNER 



Value 

10 pf 

22 pf 

47 pf 

100 pf 

220 pf 

470 pf 



50 VOLT CERAMIC DISC CAPACITORS 



1-9 
.08 
.08 
.08 
.08 
.08 
.08 



10-99 
.06 
.06 
.06 
.06 
.06 
.06 



100+ 

.05 

.05 

.05 

.05 

.05 

.05 



Value 

.OOlAlF 
.004 7uF 
.01mF 
022mF 
.0474* F 

■ Imp 



1-9 
.08 

.08 .06 

.08 .06 

.09 .07 

.09 .07 

IS .12 



.OOlmf 
.0022m f 
.0047mf 
.Olmf 



100 VOLT MYLAR FILM CAPACITORS 



10-99 100+ 

06 .05 

.05 

.05 

.06 

.06 

.10 



.12 
.12 
.12 
.12 



.10 
.10 
.10 
.10 



.07 
.07 
.07 
.07 



.022m f 
.047mf 
.lmf 
.22mf 



.13 
.21 
.27 
.33 



.11 
.17 
.23 
.27 



.08 
.13 
.17 
.22 



♦20% DIPPED TANTALUMS (Solid) CAPACITORS 



.1/35V 

. 15/35 V 

.22/35V 

.33/35V 

.47/3SV 

.68/35V 

1.0/35V 



.39 
.39 
.39 
.39 
.39 
.39 
.39 



.34 
.34 
.34 
.34 
.34 
.34 
.34 



.29 
.29 
.29 
.29 
.29 
.29 
.29 



1.5/35V 

2.2/35V 

3.3/25V 

4. 7/25 V 

6.6/25V 

15/25V 

22/6V 



.41 
.51 
.53 
.63 
.79 
1.39 
.79 



.37 
.45 
.47 
.56 
.69 
1.25 
.69 



.29 
.34 
.37 
.45 

.55 
.95 
.55 



MINI. ALUMINUM ELECTROLYTIC CAPACITORS 



Axial 

.47/50V 

1.0/S0V 

3.3/50V 

4.7/25V 

10/25V 

10/50V 

22/25V 

22/50V 

47/25V 

47/50V 

100/25V 

100/SOV 

220/25V 

220/V)V 

470/25V 

1000/16V 

2200/16V 



1-99 100-499 

.16 .14 

.19 .16 

.17 .15 



.18 
.16 
.19 
.19 
.24 
.25 
.29 
.28 
.41 
.39 
.49 
.54 
.79 
.89 



.15 
.15 

1 

.20 
.21 
.25 
.24 
.37 
.34 
.43 
.49 
.69 
.79 



500 + 

.10 

.12 

.11 

.11 

.11 

.12 

.12 

.18 

.19 

.23 

.22 

.34 

.33 

.41 

.45 

.61 

.69 



Radial 

•47/25V 

.47/S0V 

1.0/16V 

1.0/25V 

1.0/50V 

4.7/16V 

4. 7/25 V 

4. 7/50 V 

10/16V 

10/2SV 

10/50V 

47/50V 

10D/16V 

100/25V 

100/SOV 

220/16V 

470/25V 



1-99 100-499 
.15 .13 



.16 
.15 
.16 
.17 
.15 
.16 
.17 
.15 
.16 
.17 
.25 
.21 
.25 
.37 
.25 
.35 



.14 
.13 
.14 
.15 
.13 
.14 
.15 
.13 
.14 
.15 
.21 
.17 
.23 
.34 
.21 
.31 



500 + 

12 
.13 
.12 
.13 
.14 
.12 
.13 
.14 
.12 
.13 
.14 
.19 
.14 
.21 
.31 
.19 



»^See List of Advertisers on page 194 



Microcomputing, August 1981 179 



DIGITAL RESEARCH: PARTS 



it 



TOP QUALITY PARTS FOR LESS 



9 Watt Stereo 
Amplifier 



Brand New! 



Fantastic! 

One of the neatest items we have 
come up with. Operates on 8 to 20V. 
A.C. or D.C. (on board diodes). 

• Separate tone control pots 

• Balance control 

• Volume control 

Separate inputs for phono, radio, 

recorder, etc. Separate jack for head 

phones. 

Replace your car stereo amp. Easy 

hook up — approximately 10 min. 

with our "how to" instructions. 

Transformer for above — $3.50 



Universal 
Timer Kit 

• Adjustable from 1 sec. to 
1 hr. 

• Control up to 1 amp 
"Turn Things On or Off" 



IC Specials! 

LM1889-2 29 
MC1310-1 80 



LM3820-A.M. 

Radio on a chip 

w/specs. 



2/1 



00 



16 Pin Header 

tinWiin 4/100 



Voltage 
Regulator 

LM309K 

5 Volt - 1 Amp Regulator 
T03 Case. Super Special! 



Kit includes all parts necessary to 
build this exciting kit. 
Uses: Children's T.V. 
Darkroom exposures 
min. I.D.er - Egg Timer 
Windshield Wiper, 
endless uses. 

Complete kit including power supply, 
p.c. board - DPDT relay, and all parts 
to make timer operational. 



programs - 
Amateur 10 
Intermittent 
Absolutely 



Video Game 
Board 



m< 



3for12 00 



Power Transistor 
TO220 Case 



1 Amp 30 Watts 100 Volt 
TIP30C(PNP) 
TIP29C(NPN) 



Hockey • Tennis • Handball 

• General Instruments AY3-8500 

• Features Exciting Sounds 

• On Screen Scoring 

• Speed & Paddle Controls 

• 1 or 2 Players 

• Works on 8-15 Volts D.C. 

Each board comes with RF Modulator 
(Ch. 3 or 4) and schematic. The only 
parts needed to complete game are 
speaker, 2-1 Meg Pots & Switches. 



Sprague RFI Filter 
3 65 or 3/9 00 

Perfect for Computers, or any- 
thing that needs to be "glitch" 
free. By the #1 name in filter- 
ing, Sprague. JN17-5109B. 
Has I.E.C. Power Line Con- 
nector. 2x3 Amp. 115/220 VAC 
60 Hz. 2%" x 2 1 /2 " x 3" deep. 



Rectifier Diode / 

IN4007 j/ 

1000 Volts, 1 Amp 
DO-41 Case • Prime • 
Long Lead • Marked. 



RCA Triac 

79 c 

5 for 3 S0 

T2800M-TO220 Case 
6 Amp 600 Volt 



Gold Wire 
Wrap Sockets 

Not Cheap Gold 
Inlay as Sold 
By Others. 

Super 3 Level 
Gold Wire Wrap. 

14Pin-10/3 M ,25/8 75 
16Pin-10/4 95 ,25/11 29 



Switch Banks 



Video Paddle 
Controls 



2 fori 



00 



1 Meg 

Can be used with 
game board above. 



• Non Canceling O50 

• DPDT-PC or Solder fc 

• Switches Easily Removed 

• Push On/Push Off 
THAT'S INCREDIBLE! 



JFETOPAMP 

Super High Input Impedance 
(10 12 OHMS) — High Frequen- 
cy Response. TO 4 MHZ. 
Large DC Voltage Gain 106 DB 
— New generation OP-AMP 
with Vastly Superior Features! 

LF356BH-75 c or3/2 00 



Transformer 

32VCT @ lamp 
6V @ lamp 

Measures: 

2"x2 1 /4"x2 1 /4" 
2%" Mounting Centers 



Micro Mini 
Toggle Switch 



«! 



6 for 5 00 

SPDT • Made in USA 
with Hardware 



IF YOU DON'T HAVE CATALOG #8105, YOU BETTER WRITE TODAY! 

Digital Research: Parts 

P.O. Bra 401247 • Garland, Ttxat 75040 

(214) 271-2461 



TERMS 

Add SO postage, we pay balance Order? under IS add 75 handling. No 
COD We accept Visa MasterCard and American Express cards Tex. Res 
add S'- Tax. Foreign orders (Canada 10'/-) add 20* P & H 



• VISA • MASTERCARD • AMERICAN EXPRESS • 



180 Microcomputing, August 1981 



r AK-1 MOTHERBOARD 




We also carry: 

SYM-1 $229 00 

AIM-65W/1K 389 00 
AIM-65W/4K 439 00 

We also do custom 
hardware and soft- 
ware for the 6502 
microprocessor 



HI TITTTTT 



fiifiumiiiiimm 



PRICE: $139°° 

Call or write for 
shipping charges 
and our complete 
catalog. 



The VAK-1 was specifically designed for use with the KIM-1, SYM-1 and the AIM 65 Microcomputer Systems, 
he VAK-1 uses the KIM-4* Bus Structure, because it is the only popular Multi-Sourced bus whose expansion 
>oards were designed specifically for the 6502 Microprocessor. 



PECIFICATIONS: 

Complete with rigid CARD-CAGE 

Assembled (except for card-cage). Burned in and tested. 

All IC's are in sockets 

Fully buffered address and data bus 

Uses the KIM-4* Bus (both electrical Pin-out and card size) for expansion board slots 

Provides 8 slots for expansion boards on 1" centers to allow for wire-wrap boards 

Designed for use with a Regulated Power Supply (such as our VAK-EPS) but has provisions for adding 
regulators for use with an unregulated power supply. 

Provides separate jacks for one audio-cassette, TTY and Power Supply. 
Board size: 14.5 in. Long x 11.5 in. Wide x 8 in. High 
Power requirements; 5V.DC @ 0.2 Amps. 



* KIM-4 is a product of MOS Technology '/C.B.M. 



ENTERPRISES 




INCORPORATED 



^52 



2951 W. Fairmount Avenue 
Phoenix, AZ 85017 
(602) 265-7564 



' T\«siei ' f\«rge j 




^See List of Advertisers on page 194 



Microcomputing, August 1981 181 




ELECTRONICS 



INTEGRATED CIRCUITS 



P.O. Box 4430S 
Santa Clara, CA 95054 

Will calls: 2322 Walsh Ave. 
(408) 988-1640 TWX 910-338-2139 

Same day shipment. First line parts only Factory tested 
Guaranteed money back Quality IC's and other compo- 
nents at factory prices 



74O0TTI 

.'40(jN 
7402N 
7404N 

rttm 

7410N 
7414N 
7420N 
7422N 
7430N 
7442N 
744SN 
7447N 
• MM 
7450N 
7474N 
7475N 
MSN 

7489N 

7490N 

7492N 

7493N 

7495N 

74100N 

74107N 

74121N 

741 23N 

74125N 

74145N 

741S0N 

74151N 

741 b4N 

74157N 

74161N 

74162N 

74163N 

741 74N 

74175N 

74190N 

74192N 

74193N 

74221N 

74298N 

74365N 

74366N 

7436 7N 

74LSO0 TTl 

741 SOON 

74LS02N 

74LS04N 

74LS05N 

74LS08N 

74LS10N 

74LS13N 

74LS14N 

74LS20N 

74LS22N 

74LS28N 

741S30N 

74LS33N 

74LS38N 

74LS74N 

74LS75N 

74LS90N 

74LS93N 

74LS95N 

74LS107N 

74LS112N 

74LS113N 

74IS132N 

74LS136N 

74LS151N 

74LS1S5N 

74LS157N 

74LS162N 

74LS163N 

74LS174N 

74LS190N 

74LS221N 

74LS2S8N 

74LS367N 



19 

20 

25 

27 

25 

70 

25 

39 

25 

58 

82 

63 

77 

25 

35 

49 

88 
1 70 

43 
43 
43 
69 
1 35 
35 
34 
59 
45 
77 

1 20 
69 

1 25 
69 
87 
85 
87 
96 
85 

1 15 
87 
85 

1 25 

1 65 
75 
75 
75 



29 

29 

35 

25 

35 

35 

55 

1 00 

35 

35 

35 

35 

60 

50 

45 

65 

60 

75 

1 00 

45 

45 

45 

89 

50 

75 

79 

1 10 

1 10 

1 10 

1 15 

1 25 

1 25 

1 00 

89 



LM320K b 
LM320K 12 
LM320K 15 
LM320T 5 
IM320T-8 
LM320T 12 
LM320T 15 
LM323K 5 
LM324N 
LM339N 
LM340K 5 
LM340K-8 
LM340K-12 
LM340K 15 
LM340K 24 
LM340T-5 
IM340T-8 
LM340T 12 
LM340T 15 
LM340T 18 
LM340T 24 
LM350 
LM377 
LM379 
LM380N 
LM381 
LM382 
LM709H 
LM723H N 
LM733N 
LM741CH 
LM741N 
LM747H N 
LM748N 
LM1303N 
LM1304 
LM1305 
LM1307 
IM1310 
LM1458 
LM1812 
LM1889 
LM2111 
LM2902 
LM390ON 
LM3905 
LM3909N 
MCI 458V 
NE550N 
NE555V 
NE556A 
NE565A 
NE566V 
NE567V 
NE570B 
78L05 
78L08 
78M05 
75108 
7549 1CN 
75492CN 
• 4 .4. N 



1 35 
1 35 
1 35 

95 

95 

95 

95 
5 95 
1 00 
1 00 
1 35 
1 35 
1 35 
1 35 

1 35 
85 
85 
85 
85 
85 
85 

550 

2 95 
500 
1 00 
1 60 
1 60 

59 

50 

85 

35 

38 

75 

50 

1 75 

1 10 

1 27 

200 

1 95 

55 

750 

300 

1 75 

2 25 
60 

1 75 

95 

55 

1 35 

39 

85 

1 00 

1 50 

1 00 

4 75 

60 

60 

85 

1 75 

50 

55 

89 



A It CONVERTER 

803BB 

8700CJ 

8701CN 

8750CJ 

10130 

9400CJVf 

ICL7103 

ICL7107 



4 50 
13 95 
22 00 

13 95 
995 
7 40 
950 

14 25 



CO4026 
CD 402 7 
C04028 
CD4029 
CD4030 
CD4035 
CD4040 
C04042 
C04043 
CD4044 
CO404C 
CD4049 
CD4050 
C04051 
CD4060 
C04066 
CD4068 
CD4069 
CO4070 
C04071 
CD4072 
CO4073 
C04075 
CO4076 
CD4078 
D4M1 
CD4082 
C04116 
CD4490 
CD4507 
C04508 
CO4510 
CD4511 
CD4515 
C04516 
CD4518 
CD4520 
C04527 
CD4528 
C04553 
CD4566 
CD4583 
CD4585 
CD40192 
74C0O 
74C04 
74C10 
74C14 
74C20 
74C30 
74C48 
74C74 
74C76 
74C90 
74C93 
74C154 
74C160 
74C175 
74C192 
74C221 
74C905 
'4C906 
74C914 
74C922 
74C923 
74C925 
74C926 
r4C927 



50 

66 

85 

35 

45 

00 

35 

85 

85 

85 

67 

45 

60 

13 

42 

71 

40 

40 

50 

45 

45 

45 

45 

45 

40 

35 

35 

47 

50 

00 

85 

00 

94 

52 

10 

50 

0? 

51 

H 

50 

4-, 
15 
10 
00 

40 

as 

84 
3'j 
3b 
K 

8b 
2b 
2b 
?b 
bO 
7 b 
3b 

ss 

N 
00 

7b 
K 
00 

30 

bO 

gs 

4b 



21141 450ns 4 00 

4116 200ns 3 95 
84116 200nsl8 40 

MM5262 40 

MM5280 3 00 

MMb320 9 95 

MM5330 5 94 

P0411D3 4 00 

P0411D-4 5 00 

P5101L 8 95 

4200A 9 95 

82S25 2 90 

91L02A 1 50 

H00165 5 6 95 

MM571O0 4 50 

GIAY38500 1 9 95 

MCM66751A 9 95 

9368 3 50 

4100 10 00 

416 16 00 

CLOCKS 

MM5311 5 50 

MM5312 3 90 

MM5314 3 90 

MM5369 2 10 

MM5841 14 45 

MM5865 7 95 

CT7010 8 95 

CT7015 8 95 
MM537bAA.N 3 90 

MM5375AG N 4 90 

7205 16 50 

7207 7 50 

7208 15 95 

7209 4 95 
DSO026CN 3 75 
DS0056CN 3 75 
MM53104 2 50 

MICROPROCESSOR 



CONNECTORS 
30 pin edge 2 50 

44 pm edge 2 75 

86 pin edge 4 00 
100 pin edge 4 50 
100 pm edge WW 5 25 

IC SOCKETS 

Solder Tin Low Profile 
PIN 1 UP PIN 1UP 



6502 

6504 

6522 

6800 

6802 

6820 

6850 

8080A 

8085 

8086 

/80 

Z80A 

8212 

8214 

8216 

8224 

8228 

8251 

8253 

8255 

8257 

8259 



10 95 
9 95 
9 95 
6 95 

11 95 

4 95 

5 95 
395 

12 95 
75 00 

9 95 
11 95 

290 
395 

2 90 

3 45 

4 95 

6 95 
15 00 

5 75 

10 95 
14 95 



? level 14 pm ** 20 
WIRE WRAP LEVEL 3 



CRYSTALS 

1 MM; 

2 MH; 

4 MH7 

5 MHz 
10 MH/ 
18 MH; 
20 MHz 
32 MH/ 
32768 Hi 

1 8432 MH; 
3 5795 MHz 

2 0100 MHz 
2 097152 MHz 

2 4576 MHz 

3 2768 MHz 
5 0688 MHz 
5 185 MHz 

5 7143 MHz 

6 5536 MHz 
14 31818 MHz 
18 432 MHz 
22 1184 MHz 

KEYBOARD ENCODERS 



KEYBOAROS 

56 key ASCII keyboard kit S67 50 

Fully assembled 77 50 

53 key ASCII keyboard kil 60 00 

Fully assembled 70 00 

Enclosure Plastic 14 95 

Metal Enclosure 29 95 

LEDS 

Red TO 18 

Green Yellow T018 

Jumbo Red 20 

Green Orange Yellow Jumbo 25 

Cliplili LED Mounting Clips 8/$1 25 

ispecrtyred amber green yellow, clearl 

CONTINENTAL SPECIALTIES in slock 
Complete line ot breadboard test equip 
MAX 100 8 digit Frtq Ctr $149 95 

OK WIRE WRAP TOOLS in stock 
Portable Multimeter $18 00 

Complete line ol AP Products in stock 

SPECIAL PRODUCTS 

MM5865 Stopwatch Timer 

with 10 pg spec 9 00 

PC board 7 50 

Switckes Mom Pushbutton 27 

3 pos slide 25 

Encoder HO0165 5 6 95 

Parttrenics 
Model 10 Trigger 

Upander Kit 
Model 150 Bus 

Grabber Kit 
Clock Calender Kit 
2 5 MHz Frequency 

Counler Kil 
30 MHi Frequency 

Counter Kil 



S229 00 

$369 00 
$23 95 

$37 50 

$47 75 



AY5 2376 
AY5 3600 
AY5-9100 
AY592O0 
74C922 
74C923 
HD0165 5 
AY5 9400 



$12 50 
17 95 
10 50 
16 50 

5 50 
550 

6 95 
10 50 



1802CP plas 13 95 

1802DP plas 17 95 

1861P 9 50 

CDP1802C0 28 95 

COP 18020 35 00 

CDP1816P 7 95 



LINEAR 

CA3045 

CA3046 

CA3081 

CA3082 

CA3089 

LM301AN AH 

LM305H 

LM307N 

LM308N 

LM309K 

LM311H N 

LM317T 

LM317K 

LM318 



90 

1 10 

1 80 

1 90 

3 40 

35 

87 

35 

1 00 

1 25 

90 

1 65 

3 75 

1 50 



CMOS 

CD4000 

CD4001 

CD4002 

CD4008 

CD4007 

C04008 

CD4009 

CD4010 

CD40H 

CO4012 

C04013 

CO4014 

CD4015 

CO4016 

CD4017 

C04018 

C04019 

CO4020 

CD4021 

C04022 

C04023 

CD4024 

CO 4025 



25 

35 

35 

I 10 

35 

1 20 

45 

45 

35 

28 

47 

1 25 

1 00 

55 

1 05 

94 

45 

1 02 

1 35 

1 10 

28 

75 

28 



MM 

8097 
8098 
8T09 
8T10 
8T13 
8T20 
8T23 
8T24 
8T25 
8T26 
8T28 
8T97 

MT4H 



MOS MEMORY 

2101 1 2 

2102 1 
2102AL 4 
2102AN 2L 
2104A 4 
2107B 4 

2111 1 

2112 2 
2114 



65 UARTFIFO 

65 AY51013 

65 AY5 1014 

65 33< 1 
25 

50 PROM 

00 1 702A 

50 2708 

10 2716T1 

50 2716 5 VoH 

20 8 2716 5 Volt 

69 2732 

75 2758 

69 8741 A 

69 8748 
87488 
8755A 
RAMN82S23 

95 N82S123 

95 N82S126 

45 N82S129 

6b N82S131 

95 N82S136 

75 N82S137 

75 DM8577 



Connectors RS232 

DB25P 3 62 

DBi'bS 5 20 

Cover 1 67 

0E9S 195 

DA15P 2 10 

OA15S 3 10 

Complete Set 9 50 

Hickok3'-i0i|it LEO mul- 
timeter B9 95 
Stopwatch KM 26 95 
Auto Clock Kit 17 95 
Digital Clock Kit 14 95 

IK 16K Eprom Kit 

less PROMSl $89 00 
Motherboard $39 00 

E slender Board $15 00 



5 85 

6 10 
12 00 
10 50 
64 00 
19 95 
1400 
55 00 
55 00 
55 00 
55 00 

2 95 
4 95 
4 75 
4 95 
4 95 
8 75 
8 75 

2 90 

3 50 



RESISTORS « watt5°. 
10 per type 03 
25 per type 025 
100 per type 015 
1000 per type 012 
350 piece pack 
5 per type 6 75 

'} wan 5°o per type 05 

Televideo Terminal 
Model 912 $785 00 
Model 920 $885 00 



TRANSFORMERS 

6V 300 ma 3 25 
12 Volt 300 ma translormer 1 25 

l2 6VCT600ma 3 75 

12V 250 ma wall plug 2 95 
1 2V CT 250 ma wall plug 3 75 

24V CT 100 ma 3 95 

10V 1 2 amp wall plug 4 85 

12V 6 amp 12 95 

12V 500 ma wall plug 4 75 

12V 1 amp wall plug 6 50 

10 15 VAC 8 16 VA wall plug 9 75 

DISPLAY LEOS 

MAN I CA 270 2 90 

MAN3 CC 125 39 

MAN72 74 CA CA 300 1 00 

DL704 CC 300 1 25 

OL707 DL707R CA 300 1 00 

DL727 728 CA CC 500 1 90 

DL747 750 CAiCC 600 1 95 

FND359 CC 357 70 

FN0500 507 CC CA 500 1 35 

FND503 510 CC CA 500 90 

FND800 807 CC CA 800 2 20 

3 digit Bubble 60 

10 digit display 1 25 

7520 Clairex photocells 39 

TIL311 Hen 9 50 

MAN3640 CC 30 1 10 

MAN4610 CA 40 1 20 

MAN4640 CC 40 1 20 

MAN4710 CA 40 95 

MAN4740 CC 40 1 20 

MAN6640 CC 56 2 95 

MAN6710 CA 60 1 35 

MAN6740 CC 60 1 35 

MA1002A. C. E » 95 

MA1012A 195 

102P3 Iranslormer 2 25 

MA1012A Transformer 2 25 

DIP Switches 

4 position S 95 7 position 1 00 

5 position 1 00 8-posrtion 1 05 

6 position 1 00 



2114L 300ns 4 



4116 200ns Dynamic RAM 
8/S18.40 



PROM Eraser 

assembled. 25 PROM capacity $37.50 
(with timer $69.50) 6 PROM capacity OSHA/ 
UL version $69.50 (with timer $94.50) 

Z80 Microcomputer 

16 bit I/O, 2 MHz clock, 2K RAM, ROM Bread- 
board space Excellent for control. Bare Board 
$28.50. Full Kit $99.00. Monitor $20.00. Power 
Supply Kit $35.00. Tiny Basic $30.00 

S-100 Computer Boards 

8K Static God bout Econo 1 1 A Kit 149.00 
16K Static Godbout Econo XIV Kit 269.00 
24K Static Godbout Econo XX-24 Kit 414.00 
32K Static Godbout Econo XX- 32 Kit 537.00 
16K Dynamic RAM Kit 289 00 

32K Dynamic RAM Kit 328.00 

64K Dynamic RAM Kit 399 00 

Video Interface Kit $161.00 

Color Video Kit 129 95 

81 IC Update Master Manual $79.95 

Comp IC data selector, 2 vol master reference 
guide Over 51,000 cross references. Free update 
service through 1981. Domestic postage $4.75. 

Modem Kit $60.00 

State of the art, orig , answer. No tuning neces- 
sary. 103 compatible 300 baud. Inexpensive 
acoustic coupler plans included. Bd. only $17.00. 
Article in May Radio Electronics. 

LRC 7000 * Printer $389.00 

64/40/32/20 column dot matrix impact, std. 
paper Interface all personal computers. 
LRC 7000 printer interlace cable for Super Elf 
with software $35.00 




>7 




NiCad Battery Fixer/Charger Kit 

Opens shorted cells that won't hold a charge 
and then charges them up, all in one kit w/full 
parts and instructions. $9.95 

Rockwell AIM 65 Computer 

6502 based single board with full ASCII keyboard 
and 20 column thermal printer. 20 char, alphanu- 
meric display, ROM monitor, fully expandable 
$405.00. 4K version $450.00. 4K Assembler 
$85.00. 8K Basic Interpreter $100.00. 

Special small power supply for AIM65 assem. in 
frame $54.00. Complete AIM65 in thin briefcase 
with power supply $499.00. Molded plastic 
enclosure to fit both AIM65 and power supply 
$47.50. Special Package Pnce: 4K AIM, 8K Basic, 
power supply, cabinet $625.00. 

AIM65/KIM/VIM/Super Elf 44 pin expansion 
board; 3 female and 1 male bus. Board plus 3 
connectors $22.95. 

60 Hz Crystal Time Base Kit $4.40 

Converts digital clocks from AC line frequency 
to crystal time base. Outstanding accuracy. 

Video Modulator Kit $9.95 

Convert TV set into a high quality monitor w/o 
affecting usage. Comp. kit w/full instruc. 

Multi-volt Computer Power Supply 

8v 5 amp, ±18v .5 amp, 5v 1.5 amp, -5v 
.5 amp, 12v .5 amp, -12v option. ±5v, ±12v 
are regulated. Basic Kit $35.95. Kit with chassis 
and all hardware $51.95. Add $5.00 shipping. Kit 
of hardware $16.00. Woodgrain case $10.00. 
$1.50 shipping. 



RCA Cosmac 1802 Super Elf Computer $106.95 



Compare features before you decide to buy any 
other computer. There is no other computer on 
the market today that has all the desirable bene- 
fits of the Super Elf for so little money. The Super 
Elf is a small single board computer that does 
many big things It is an excellent computer for 
training and for learning programming with its 
machine language and yet it is easily expanded 
with additional memory, Full Basic, ASCII 
Keyboards, video character generation, etc. 
Before you buy another small computer, see if it 
includes the following features: ROM monitor; 
State and Mode displays; Single step; Optional 
address displays; Power Supply; Audio Amplifier 
and Speaker; Fully socketed for all IC's; Real cost 
of in warranty repairs; Full documentation. 
The Super Elf includes a ROM monitor for pro- 
gram loading, editing and execution with SINGLE 
STEP for program debugging which is not in- 
cluded in others at the same price. With SINGLE 
STEP you can see the microprocessor chip opera- 
ting with the unique Quest address and data bus 
displays before, during and after executing in- 
structions. Also, CPU mode and instruction cycle 
are decoded and displayed on 8 LED indicators. 

An RCA 1861 video graphics chip allows you to 
connect to your own TV with an inexpensive video 
modulator to do graphics and games. There is a 



plus load, reset, run, wait, input, memory pro- 
tect, monitor select and single step Large, on 
board displays provide output and optional high 
and low address. There is a 44 pin standard 
connector slot for PC cards and a 50 pin connec- 
tor slot for the Quest Super Expansion Board. 
Power supply and sockets for all IC's are in- 
cluded in the price plus a detailed 1 27 pg instruc- 
tion manual which now includes over 40 pgs. of 
software info, including a series of lessons to 
help get you started and a music program and 
graphics target game Many schools and univer- 
sities are using the Super Elf as a course of study. 
OEM's use it for training and R&D. 
Remember, other computers only offer Super Elf 
features at additional cost or not at all. Compare 
before you buy. Super Elf Kit $106.95, High 
address option $8.95, Low address option 
$9.95. Custom Cabinet with drilled and labelled 
plexiglass front panel $24.95. All metal Expan- 
sion Cabinet, painted and silk screened, with 
room for 5 S-100 boards and power supply 
$57.00. NiCad Battery Memory Saver Kit $6.95. 
All kits and options also completely assembled 
and tested. 

Questdata. a software publication for 1802 com- 
puter users is available by subscription for 
$12.00 per 12 issues. Single issues $1.50. Is- 
sues 1-12 bound $16.50. 



speaker system included for writing your own 

music or using many music programs already Free 14 DdQe DrOCnlire. 

written. The speaker amplifier may also be used 

to drive relays for control purposes. 

A 24 key HEX keyboard includes 16 HEX keys 

Super Expansion Board with Cassette Interface $89.95 



Moews Video Graphics $3.50. Games and Music 
$3.00. Chip 8 Interpreter $5.50. 



This is truly an astounding value! This board has 
been designed to allow you to decide how you 
want it optioned The Super Expansion Board 
comes with 4K of low power RAM fully address- 
able anywhere in 64K with built-in memory pro- 
tect and a cassette interface Provisions have 
been made for all other options on the same 
board and it fits neatly into the hardwood cabinet 
alongside the Super Elf The board includes slots 
for up to 6K of EPROM (2708, 2758, 2716 or Tl 
2716) and is fully socketed. EPROM can be used 
for the monitor and Tiny Basic or other purposes. 
A IK Super ROM Monitor $19.95 is available as 
an on board option in 2708 EPROM which has 
been preprogrammed with a program loader/ 
editor and error checking multi file cassette 
read/write software, (relocatable cassette file) 
another exclusive from Quest. It includes register 
save and readout, block move capability and 
video graphics driver with blinking cursor. Break 



Quest Super Basic V5.0 

A new enhanced version of Super Basic now 
available. Quest was the first companv 
worldwide to ship a full size Basic for 1802 
Systems. A complete function Super Basic by 
Ron Conker including floating point capability 
with scientific notation [number range 
±.17E M ), 32 bit integer ±2 billion; multi dim 
arrays, string arrays; string manipulation; cas- 



"L 



points can be used with the register save feature 
to isolate program bugs quickly, then follow with 
single step If you have the Super Expansion 
Board and Super Monitor the monitor is up and 
running at the push of a button. 
Other on board options include Parallel Input 
and Output Ports with full handshake They 
allow easy connection of an ASCII keyboard to the 
input port RS 232 and 20 ma Current Loop for 
teletype or other device are on board and if you 
need more memory there are two S-100 slots for 
static RAM or video boards. Also a 1K Super 
Monitor version 2 with video driver for full capa- 
bility display with Tiny Basic and a video interface 
board Parallel I/O Ports $9.85, RS 232 $4.50, 
TTY 20 ma l/F $1.95, S-100 $4.50. A 50 pin 
connector set with ribbon cable is available at 
$15.25 for easy connection between the Super 
Elf and the Super Expansion Board. 
Power Supply Kit for the complete system (see 
Multi-volt Power Supply). 



Ohio Scientific Computers 

CIP Series 2 $447.00. Like an Apple at less than 
half the price! CIPMF Series 2 $1199.00. 
Minifloppy version with additional RAM/ROM. 
Complete software and peripherals available. 
Send for free brochure. 



sette I/O; save and load, basic, data and ma- 
chine language programs; and over 75 state- 
ments, functions and operations. 
New improved faster version including re- 
number and essentially unlimited variables. 
Also, an exclusive user expandable command 
library. 

Senal and Parallel I/O included. 
Super Basic on Cassette $55.00. 



Gremlin Color Video Kit $69.95 

32 x 16 alpha/numerics and graphics; up to 8 
colors with 6847 chip; 1K RAM at E000. Plugs 
into Super Elf 44 pin bus. No high res. graphics. 
On board RF Modulator Kit $4.95 



1802 16K Dynamic RAM Kit $149.00 

Expandable to 32K. Hidden refresh w/clocks up to 4 
MHz w/no wait states. Addl. 16K RAM $25.00 
Tiny Basic Extended on Cassette $15.00 
(added commands include Stringy, Array, Cas- 
sette I/O etc.) S-100 4-Slot Expansion $ 9.95 
Super Monitor VI. I Source Listing $15.00 



Elf II Adapter Kit $24.95 

Plugs into Elf II providing Super Elf 44 and 50 pin 
plus S-100 bus expansion. (With Super Ex- 
pansion). High and low address displays, state 
and mode LED s optional $18.00. 

Super Color S-100 Video Kit $129.95 

Expandable to 256 x 192 high resolution color 
graphics. 6847 with all display modes computer 
controlled. Memory mapped. 1K RAM expanda- 
ble to 6K . S- 1 00 bus 1 802 , 8080 , 8085 , Z80 etc . 
Dealers: Send for excellent pricing/margin 
program. 

Editor Assembler $25.00 

(Requires minimum of 4K for E A plus user 
source) 

1802 Tiny Basic Source listing $19.00 

Super Monitor V2.0/2.1 Source Listing $20.00 



TERMS $5.00 min. order U.S. Funds. Calif residents add 6% tax. 

$10.00 min. BankAmericard and Master Charge accepted. $1.00 insurance optional. 
Postage: Add 5%. COD. $10.00 min. order. 



FREE: Send for your copy of our NEW 1981 
QUEST CATALOG. Include 48c stamp. 



Get the Inside Track 




( 1 1 r • p iryyvv •"''•*" 



S-100 bus compatible • Reads and writes single 
or double density • Density is software selectable 
• CP/M" 2.2 compatible in single or double 
density • Controls up to four 5-1/4" or 8", single or 
double-sided drives • Single or double-sided drives 
may be mixed in the same system • Onboard Z- 
80A to assure reliable operation • EIA level serial 
printer interface on board, baud rates to 9600 
(perfect for despooling operations) • 2K of RAM 
onboard • Uses IBM standard formats • 
Designed to meet IEEE signal disciplines • Works 
with 8080, 8085, and Z-80 CPU's • 4-layer PC 
board with internal power and ground planes 
provides very stable, low-noise operation. 



IOD-1200B 

IOD-1200K 

IOD-1200A 

IOD-1205A 

SFC-58001200E 

SFC-59002001F 



Bare board $59.95 

Kit $299.95 

A & TforS" $375.95 

A& TforSW $395.00 

DD boot PROM .... $20.00 
CP/M 2.2 for DD . $150.00 



JADE 

Memory Bank ™ 

8 or 16 Bit Dynamic Memory 

New, from JADE (naturally), an IEEE S-100 
64K dynamic memory that looks toward the 
future. • IEEE S-100 standard pinout and signal 
discipline • Expandable to 16 Megabytes via 
switchable port OR extended address lines • 8 or 
16 bit words, automatically, depending on the type 
of CPU on the bus • 4-layer PC board for 
extremely low-noise operation. 

The new JADE Memory Bank™ is one of the 
safest places you can store your valuable program 
information. With its onboard refresh controller, 
this board allows DMA operations without regard 
to time factors. It will run reliably at any system 
clock rate up to 6 MHz -because it is clocked with 
the system clock itself (no one-shots are used for 
timing operations). Its unique IEEE design 
enables it to switch from a 64 K by 8-bit board to a 
32K by 16-bit board automatically (responds to 
IEEE's 16 Rqst line and, if enabled, replies with 16 
Grant). 

Onboard Ml wait-state generator allows the 
use of slower memory, and a unique onboard 
Iprecharge extender makes this board run reliably 
[with any manufacturer's 4116 memory chips. 

Compatible with Cromemco and other CPU 
J systems - features enough optional strapping to 
enable it to run with any Z-80/Z8000 system. 

MEM-99730B Bare Board $49.95 

MEM-99730K Kit, no RAM $199.95 

MEM-16730K )6X kit $219.95 

MEM-32731K 32 K kit $239.95 

MEM-48732K 48K kit $259.95 

|MEM-64733K 64K kit $279.95 

[88embled & Tested add $50.00 



JADE 

The Big Z 



»^48 
TM 

Z-80A Based CPU 




S-100 bus compatible • Switch selectable 2 or 4 
MHz operation • Serial I/O port • Accomodates a 
2708, 2716, or 2732 EPROM in shadow mode 
allowing full use of 64K RAM • MWRITE signal is 
generated automatically if used without front 
panel • Onboard 8251 US ART controls serial port 
at baud rates from 75 to 9600 baud • Switch 
selectable IK, 2K, or 4K boundary fully buffered • 
Power-on jump to EPROM 

CPU-30201K Kit $139.95 

CPU-30201 A A&T $189.95 

CPU-30200B Bare board $35.00 



Memory Chips on Sale 



1U-2J 



2."»- 19 



21141 


, / MHz 


3.35 


2.99 


2.75 


2.49 


2708 


2 MHz 


1.90 


3.90 


3.15 


2.90 


2532 


2 MHz 


24.90 


19.90 


15.90 


12.90 


2716 


2 MHz 


8.90 


7.15 


0.15 


5.75 


2716 


4 MHz 


19.90 


15. 15 


13.15 


1 1 .75 


2732 


2 MHz 


24.90 


19.90 


15.90 


12.90 


2732 


I MHz 


39.90 


29.9<> 


24.90 


19.90 


2758 


2 MHz 


6.90 


6.25 


5.50 


1.50 


11 16 


2(H) ns 


3.25 


2.99 


2.19 


1.99 


11 64 


200 ns 


28.90 


2 4.90 


22.90 


19.90 



JADE 

Disk Sub-Systems 

Shugart, Siemens, Qume 




Handsome metal cabinet with proportionally 
balanced air flow system • Rugged dual drive 
power supply • Power cable kit • Power switch, 
line cord, fuse holder, cooling fan • Never-Mar 
rubber feet • All necessary hardware to mount 2- 
8" disk drives, power supply, and fan • Does not 
include signal cable 

Dual 8" Subassembly Cabinet 

END-000420 Bare cabinet $59.95 

END-000421 Cabinet kit $225.00 

END-000431 A&T $359.95 

8" Disk Drive Subsystems 
Single Sided, Double Density 
END-000423 Kit w/2 FDlOO-SDs . . $975.00 
END-000424 A & T w/2 FDlOO-SDs $1175.00 
END-000433 Kit w/2 SA-SOIRs . $999.95 
END-000434 A & T w/2 SA -801 Rs $1195.00 

8" Disk Drive Subsystems 
Double Sided, Double Density 

END-000426 Kit w/2 DT8s $1475.00 

END-000427 A & T w/2 DT8s ... $1675.00 
END-000436 Kit w/2 SA-851Rs $1495.00 
END-000437 A & T w/2 SA-851Rs $1695.00 



JADE 

S.P.I.C. 

Our "SPICy" New I/O Board 




New, from JADE, one of the most advanced, 
technologically sophisticated Serial/Parallel 
Interrupt Controller systems in the world. On a 
single IEEE S-100 standard board, JADE has 
packed two bi-directional parallel ports with full 
handshaking, four serial channels (asynchronous, 

IBM-compatible bi-synch, synchronous, 
HDLC/SDLC) with complete modem control lines, 
and 16 counter-timer channels. 

Utilizing the highly advanced Zilog peripheral 
chips, (Z-80 SIO, PIO & CTCs), the SPIC board is 
fully programmable to serve as the foundation for a 
multi-user multi-tasking system. Although the 
board can be operated in an 8080/8085 system, we 
recommend its use with a Z-80/Z8000 system 
utilizing the powerful Z-80/Zh000 interrupt Mode 2. 
Each of the seven Z-80 peripheral chips can 
generate its own interrupt vector, with daisy-chain 
priority levels. Each counter-timer channel can be 
programmed to monitor an interrupt vector line on 
the S-100 bus, to serve as an interval timer or real- 
time clock, and to operate as a software controllable 
baud rate generator. Each SIO channel can be 
driven independently with separate Tx/Rx clocks 
for each channel, so your peripherals can have 
varied baud rates, from 110 to 76,800 baud 
In addition, this board can serve as a data 
concentrator link to an IBM, DEC, or Data General 
mainframe computer, utilizing a high-speed serial 
channel that is programmable to virtually any 
protocol. 

IOI-1045B Bare board & manual $49.95 

IOI-1045K Kit, standard $179.95 

IOI-1045A A&T, standard $239.95 

IOI-1046K Kit w/ full chip set $219.95 

IOI-1046A A&T w/full chip set ... $299.95 



Jade Business Software 

Now, for the first time, at an amazingly low price, 
CP/M and SDOS users can get an affordable 
business software package. Just look at these 
programs! All come complete with basic code 
(written to run under CBASIC I), for easy 
customizing and modification. All software is 
self-documenting. The package price includes a 
word-processing system. When printed on the 
system's printer, all files with the extension 
xxxTOT. constitute a complete manual. No 
manuals are supplied with the package other than 
as they appear on the disks. All software is 
supplied on 8" premium quality JADE Diskettes. 
Software sold as is. (Sorry, but at these low prices 
we can not offer our usual friendly support and 
handholding.) 

Includes; General Ledger, Payroll, Invoicing, 
Inventory Controll, Accounts Recievable, Cash 
Disbursements, Fixed Assets, Cash Receipts, & 
Mailing List Management. 

Special Package Price $249.95 



Printers 



Accessories for Apple 



Single Board Computers 




BEST BUY in PRINTERS - Epson 

MX-70 132 column. HO CPS. 5x7 dot matrix, adjustable 

tractor feed, & graphics 

PRM-27070 List $459 $399.95 

MX-80 132 column, HO CPS. bi directional logic seeking 
printing. 9 x 9 dot matrix, adjustable tractor feed. & 64 
graphics characters 

PRM-27080 List $645 $474.95 

MX-80FT same as MX HO with friction feed and full 
graphics added 

PRM-27082 List $745 $574.95 

MX-100 233 column, correspondence quality, ultra high 
resolution graphics, up to 15" paper, friction feed & 
removable adjustable tractor feed, IH xlH dot matrix, HO 
CPS. programmable forms handling 

PRM-27100 List $945 $795.00 

PRA-27084 Serial interface $69.95 

PRA-27088 Serial intf & 2K buffer . . $144.95 

PRA-27081 Apple card $74.95 

PRA-27082 Apple cable $22.95 

PRA-27086 IEEE 4HH card $52.95 

PRA-27087 TRS-HO cable $32.95 

PRA-27085 Graftrax II $95.00 

PRA-27083 Extra ribbon $14.95 

SPINWRITER - NEC 

65 cps. bi directional, letter quality printer with deluxe 

tractor mechanism, both parallel and serial interfaces on 

board, 16K buffer, ribbon, print thimble, graphics, micro 

space justification, data cable, and self test diagnostic 

ROM. 

PRD-55511 without 16K buffer ... $2795.00 

PRD-55512 with 16K buffer $2895.00 



Accessories for TRS-80 



DISK DRIVES for TRS-80 

29% more storage. H times faster, 40 track with free patch, 120 
dax warranty. 

MSM-12410C Save $125.00 »! $325.00 



8" DISK DRIVES for MODEL II 

2 double density drives with cabinet, power supply. & cables 

END-000433 Kit $1050.00 

END-000434 Assembled $1250.00 

WCA-5036A Cable (required) $29.95 



16K Atari . . . $359.95 



ATARI 800 - Atari 

Complete personal computer with high resolution color 
graphics, built in HF modulator, 4 controller p<,rts. internal 
speaker. 16K HAM & HK ROM 

SYO-2080A 16K Atari 800 $759.95 

Atari 800 with 32K of RAM $799.95 

Atari 800 with 48K of RAM $849.95 

SYO-2040A 16K Atari 400 $359.95 

MSM-330810 DUM drive $595.00 

MSM-330815 Dual drive $1395.00 

I OX -5050 A 850 interface $199.95 

MEX-16853K 16K RAM module $69.95 

SFI-24101 1005 Visicalc $184.95 





16K MEMORY UPGRADE 

Add 16K of RAM to your TRSH0, Apple, or Exidy in just 
minutes. We're sold thousands of these 16K RAM 
upgrades which include the appropriate memory chips (as 
specified by the manufacturer), all necessary jumper 
blocks, fool proof instructions, and our 1 year guarantee. 

MEX-16100K TRS-80 kit $25.00 

MEX-16101K Apple kit $25.00 

MEX-16102K Exidy kit $25.00 

16K RAM Card - Microsoft 

(There is life after 4HK) 

MEX-16300A A & T $174.95 

Z-80* CARD for APPLE 

Two computers in one, Z-HO & 6502, more than doubles the 
power & potential of your Apple, includes Z-80* CPU card, 
CP M 2.2, & BASIC HO 
CPX-30800A A & T $279.95 

APPLE CLOCK -£al Comp Sys 

Real time clock w battery back-up 
IOK-2030A A&T $109.95 



DISK DRIVE for APPLE 

5> i" disk drive with controller for your Apple 

MSM-12310C with controller $475.00 

MSM-123101 w/ out controller $375.00 



8" DRIVES for APPLE 

Controller, DOS, two 8" double densisty drives, cabinet, 

power supply, & cables 

Special Package Price Kit $1399.95 



PRINTER INTERFACE - CCS. 

Centronics type I O card w/ firmware 
IOI-2041A A&T $99.95 



AIO, ASIO, APIO - S.S.M. 

Parallel & serial interface for your Apple (see Byte pg 11) 

IOI-2050K Par&Serkit $139.95 

IOI-2050A Par&SerA&T $169.95 

IOI-2052K Serial kit $89.95 

IOI-2052A Serial A&T $99.95 

IOI-2054K Parallel kit $69.95 

IOI-2054A Parallel A&T $89.95 

A488 - S.S.M. 

IEEE 4HH controller, uses simple basic commands, 
includes firmware and cable, 1 year guarantee, (see April 
Byte pg 11) 
IOX-7488A A&T $399.95 

CPS MULTICARD - Mtn. Computer 

Three cards in one! Real time clock calendar, serial interface, 
& parallel interface all on one card. 

IOX-2300A A&T $229.95 



VISICALC - Personal Sftwr 

The ultimate program for your Apple II 
SFA-24101005M Complete package $139.95 



AIM-65 - Rockwell 

6502 computer with alphanumeric display, printer. & 
keyboard, and complete instructional manuals 

CPK-50165 IK AIM $424.95 

CPK-50465 4K AIM $499.95 

SFK-74600008E HK BASIC ROM $99.95 
SFK-64600004E 4K assembler ROM $84.95 

PSX-030A Power supply $64.95 

ENX-000002 Enclosure $54.95 

IK AIM. HK BASIC, power supply. & enclosure 

Special package price $675.00 

Z-80* STARTER KIT - SD Systems 

Complete ZHO* computer with RAM. ROM. 1 O. display, 
keyboard, manual, and kluge area. 

CPS-30010K Kit $369.95 

CPS-30010A A&T $459.95 

SYM-1 - Synertek Systems 

Sin/flc board computer with IK of RAM. IK of ROM. keypad. 
LEI) display. 20ma & cassette interface on board. 

CPK-50020A A&T $249.95 



Video Terminals 



VIEWPIONT - ADDS 

Detachable keyboard, serial RS2.T2C interface, baud rates 
from 1 10 to 19.2(H). auxiliary serial output f*>rt. 24 x HOdisplay. 
tiltable sereen. international character set 

VDT-501210 Sale Priced $639.95 

TELE VI DEO 950 

Detachable keyboard, split screen with line link, etched CRT. 
programmable function keys, on screen status line, buffered 
auxiliary port. 14 x 10 dot matrix, self test, serviced nation 
wide by General Electric 
VDT-901250 List $1195.00 $995.00 



Video Monitors 



Leedex / Amdek 

Reasonably priced video monitors 

VDM-801210 Video 100 12" B&W . . $149.95 
VDM-801230 Video 100-80 12" B& W $189.95 
VDM-801250 12" Green Phospor .... $189,951 
VDC-801310 13" Color I $399.95| 

13" COLOR MONITOR - Zenith 

The hi res color you 've been promising yourself 
VDC-201301 $449.00| 

12" GREEN SCREEN - NEC 

20 MHz. P31 phosphor video monitor with audio, 
exceptionally high resolution A fantastic monitor at a\ 
very reasonable price 
VDM-651200 12" monitor $259.95| 



KPROM Erasers 



EPROM ERASERS 

L.S. Engineering V\' eraser for up to 4H EPROMs 

XME-3200 A&T $39.91 

Spectronics hi intensity industrial eraser 

XME-3100 Without timer $69.5< 

XME-3101 With timer $94.5( 




S-100 PROM Boards 




PB-1 -S.S.M. 

2708, 2716 EPROM board with built-in programmer 

MEM-99510K Kit $154.95 

MEM-99510A A&T $219.95 

PROM- 100 - SD Systems 

2708, 2716, 2732, 2758, & 2516 EPROM programmer 

MEM-99520K Kit $219.95 

MEM-99520A Jade A&T $269.95 

EPROM BOARD - Jade 

16K or 32K uses 2708's or 2716's, IK boundary 

MEM-16230K Kit $79.95 

MEM-16230A A&T $119.95 



S-100 Video 



VB-3 - S.S.M. 

80 characters x 24 lines expandable to 80 x 48 for a full page 
of text, upper & lower case, 256 user defined symbols, 160 x 
192 graphics matrix, memory mapped, has key board 
input. 

IOV-1095K 4 MHz kit $349.95 

IOV-1095A 4 MHz A&T $439.95 

IOV-1096K 80x48 upgrade $39.95 

VDB-8024 - SD Systems 

80 x 24 I/O mapped video board with keyboard I/O, and 
onboard Z-80 A*. 

1OV-1020K Kit $399.95 

IOV-1020A Jade A&T $459.95 

VIDEO BOARD - Jade 

64 characters x 16 lines, 7x9 dot matrix, full upper /lower 
case ASCII character set, numbers, symbols, and greek 
letters, normal reverse/ blinking video, S-100. 

IOV-1050K Kit $99.95 

IOV-1050A A&T $125.00 

1OV-1050B Bare board $29.95 



Motherboards 



ISO-BUS - Jade 

Silent, simple, and on sale - a better motherboard 
6 Slot (5 '4" x SW) 

MBS-061B Bare board $19.95 

MBS-061K Kit $39.95 

MBS-061A A&T $49.95 

12 Slot (9 :{ 4" x8% ") 

MBS-121B Bare board $29.95 

MBS-121K Kit $69.95 

MBS-121A A&T $89.95 

18 Slot (14'/j" x8%") 

MBS-181B Bare board $49.95 

MBS-181K Kit $99.95 

MBS-181A A&T $139.95 



Mainframes 



MAINFRAME - Cal Comp Sys 

12 slot S-100 mainframe with 20 amp power supply 

ENC-112105 Kit $379.95 

ENC-1 12106 A&T $409.95 

DISK MAINFRAME - N.P.C. 

Holds 2 8" drires and a 12 slot S100 system. Attractive 
metal cabinet with 12 slot motherboard & card cage, power 
supply, dual fans, lighted switch, and other professional 
features 

ENS- 1 12320 with 25 amp p.s $699.95 



S-100 Memory 




EXPANDORAM II - S D Systems 

4 MHz RAM board expandable from 16K to 64K 

MEM-16630K 16K kit $275.95 

MEM-32631K 32K kit $295.95 

MEM-48632K 48K kit $315.95 

MEM-64633K 64 K kit $335.95 

Assembled & tested add $50.00 

64K RAM - Calif Computer Sys 

4 MHz bank port / bank byte selectable, extended 
addressing, 16K bank selectable, PHANTOM line allows 
memory overlay, 8080 / Z-80 / front panel compatible. 
MEM-64565A A&T $575.00 

32K STATIC RAM - Jade 

2 <>r 4 MHz expandable static RAM board uses 21 14L's 

MEM-16151K I6K4MHzkit $169.95 

MEM-32151K 32K 4 MHz kit $299.95 

Assembled & tested add $50.00 

16K STATIC RAM - Mem Merchant 

4 MHz 16K static RAM board, IEEE S-100, bank selectable. 
Phantom capability, addressable in 4K blocks, "disableable" 
in IK segments, extended addressing, low power 

MEM-16171A A&T $174.95 



S-100 Disk Controller 



DOUBLE DENSITY - Cal Comp Sys 

5' i" and 8" disk controller, single or double density, with 
onboard boot loader ROM, and free CP/M 2.2* and 
manual set. 

IOD-1300A A&T $369.95 

VERSAFLOPPY II - SD Systems 

New double density controller for both 8" & 5'A" 

IOD-1160K Kit $339.95 

IOD-1 160A A&T $379.95 



Disk Drives 



8" DISK DRIVES 

Highly reliable double density floppy disk drives 
Shugart 801 R single sided, double density 

MSF-10801R SA-801R $425.00 

Special Sale Price 2 for $790.00 

Shugart 851R double sided, double density 

MSF-10851R SA-85IR $595.00 

Special Sale Price 2 for $1150.00 

Siemens FDD100-8D2 single sided, double density 

MSF-201 120 6 mo warranty $385.00 

Special sale price 2 for $750.00 

Qume Datatrak 8 double sided, double density 
MSF- 750080 SA 851 R compatible . . $599.95 
Special sale price 2 for $1160.00 

JADE DISK PACKAGE 

Double density controller, two 8" double density floppy 
disk drives, CP/ M 2.2 (configured for controller), hardware 
and software manuals, boot PROM, cabinet, power supply, 
fan, & cables 

Special Package Price Kit $1395.00 



5 l A" Diskettes Box of 10 .. $22.00 
8" Diskettes Box of 10 .... $24.00 



S-100 CPU 




CB-2 Z-80 CPU - S.S.M. 

2 or 4 MHz Z-80 CPU board with provision for up to 8K of 
ROM or 4K of RAM on board, extended addressing, IEEE 
S-100, front panel compatible. 

CPU-30300K Kit $239.95 

CPU-30300A A&T $299.95 

2810 Z-80* CPU - Cal Comp Sys 

2 4 MHz Z-80 A * CPU with RS232C serial I Oport and on- 
board MOSS 2.2 monitor PROM, front panel compatible 
CPU-30400A A&T $269.95 

SBC-200 - SD Systems 

4 MHz Z-80* CPU with serial & parallel I/O ports, up to 8K 
of onboard PROM, software programmable baud rate 
generator, IK of onboard RAM, Z-80 CTC. 

CPC-30200K Kit $339.95 

CPC-30200A Jade A&T $399.95 



S-100 I/O 



1/0-4 - S.S.M. 

2 serial I/O ports plus 2 parallel I/O ports 

IOI-1010K Kit $179.95 

IOI-1010A A&T $249.95 

IOI-1010B Bare board $35.00 



Novation Cat Modem 





I 
■ 
I 
I 

I 
I 

I 



(We 
have 
only 265 
availible at this 

special price) 

IOM-5200A List price $189.95 $139.95 

D-CAT 300 baud, direct connect modem 
IOM-5201 A Special sale price $189.00 

AUTO-CAT Auto answer origiate, direct connect 
IOM-5230A Special sale price $239.95 



Place Orders Toll Free 

Continental U.S. Inside California 

800-421-5500 800-262-1710 

For Technical Inquires or Customer Service call: 

213-973-7707 



»^48 



f 





Computer Products 



4901 W. Rosecrans, Hawthorne, Ca 90250 

TKRMS of SALE: (ash, checks, credit cards, or 
Purchase Orders from qualified firms and institutions. 
Minimum Order $15.00. California residents add 6% 
tax. Minimum shipping & handling charge $3.00. 
Pricing & availibility subject to change 




Why use their flexible discs, 

Ampex, Athana, BASF, Caelus, Control Data, Dysan, 

IBM, Inmac, K-Line, Maxell, Nashua, Scotch, 

Shugart, Syncom, 3M, Verbatim or Wabash 

when you could be using 




for as low as $1.99 each? 

Find the flexible disc you're now using on our cross reference list... 
then write down the equivalent Memorex part number you should be ordering. 















































Product Description 


Pert Number 
(3201) 


CE quant. 
1 0O pr ic. 
patrdiacCS) 


Ampe« 


Athene 


B»»F 


Ceekie 


Dysan 


IBM 


Kline 


Ma. .m 


Neenua 


Scotch 


SrweuKt 


Syncom 


Verbatim 


W— , 


_ 


Control 

Data 




FleilMe Oi%q 14 

Single Headed Drivee 

Single Density Media 


IBM CompeiibM H26 B S ?e sectors) 

IBM Competible (126 B/S. 26 sectoral •'W'N 

IBM Compatible (128 B'S 26 aectord «/ W P N t Hub ring 

IBM Compatible 1128 B/S 26 sectors) REVERSIBLE 

IBM Sytlem 6 Compalible 

IBM Competible (2S6 B'S iSaectora) 

IBM Compatible (Si 2 B-S 6 sectoral 

Stiugart Compatible 32 nerd sector 

Snugari Compatible 32 nard sector REVERSIBLE 

rVang Compatible 32 hard sector * Hub nog 

CPT SOOO Compatible 


3060 
3062 
3064 
1726 
3066 
3109 
3110 
3015 
3025 
3067 
3045 


2.19 
2.24 
2.55 
3.35 
2.19 
2 19 
2.19 
2.19 
3.35 
250 
279 


5FD-11I110 

5FD 1 131 10 

SF0-11 1210 

SFO 211010 
SFO 213010 


473071 

473072 
473077 
473073 
473074 
470901 


53426 

544 3' 
54561 

53602 
54491 


CMF11 
CM-F21 


800506 

800509 

800564 

800585 

101/1 


2305830 

rajMM 

2305845 
1669954 


40013 

40015 
40014 
40040 
40044 
40016 
40017 


F01 128 
FH1 32 


FD-i 
F0-2 

FO-132 


740-0 
740-0 

740'2 
740-0 0S6 
74O-36O0 

740-32 
740/2 32 
740-32RM 


S'A 100 
S/A 101 


15002 

15150 
15003 

15005 
ISO04 
15025 
15151 

15226 


FF34-2000 
F060-1000 
F036-1000 
F060-I000 
F032-10O0 
FF32 2000 


F1711I1X 
F116111X 
FI1211 IX 
FII3111X 

F37A41 IX 


7860-K 

7861 K 
7689 K 
7890 K 
7860 K 


421322 




FtailMe Otse 1* 

Single HuMd Df.es 
Double Density Medie 


IBM Competible (126 B'S 26 sectors) 

Sort Sector ll ?8 B'S 26 seclorsl REVERSIBLE 

Snugari Compatible 32 Hard sector 

Shugart Compatible 32 hard sector REVERSIBLE 

Wang Compatible 32 hard sector o'Hub ring 


3090 

30*3 
3091 
3094 
3068 


295 
3.99 
2.95 
399 
3.20 


SFD-121010 
5FD-221010 


474071 
470601 


54568 
54596 


- 


3740/10 

101 ID 


- 


40047 
40024 


FD1-128/M2100 
FH1 320 


FO 10 


741 
741 32 


S'A 103 


15075 


F034 8000 
F032 8000 


F33A410X 
F22A411X 


/887 K 


423322 




FlailbW One 2* 

Double Headed Drives 


Sott Sector (Untormetled) 
Sott Sector 1126 B'S 26 sectors) 
Sott Sector (2S6 B/S IS sectors) 
32 Hard Sector 


3101 
3113 

3106 
3106 


3.84 
3 84 
3.84 
3.84 


- 


473477 


54428 
54226 


- 


800814 
800815 


1 766870 
2736700 


40043 


FD2 2560 
FH2 32 


- 


742 


S'A ISO 


15153 

15154 


FOI 0-4026 

F010 4015 


F121111X 
F122UIX 


7656 K 


424612 




F K.lbta DIM M 

Double Headed Orives 
Double Density Media 


Soft Sector (Unformatted) 
Soli Sector I 128 B'S 26 sectors) 
Solt Sector 1 2S6 B/S 26 sectors) 
Sott Sector 1 Si 2 B/S IS sectors) 
Sott Sector H024 B'S 8 sectoral 
32 Hard Sector 

Burrougha B 80 Compatible 32 Hard Sector 
Solt Sector 11024 B/S 8 sectors) <•' Hub Ring 


3102 
3115 
3103 
3114 
3104 
310S 
30S2 
3116 


349 
3.49 
3.49 
349 
349 
3.49 
3.49 
375 


SFO 321010 


4 73485 

473471 
473472 
473473 
4 7065 1 


54325 

544/9 
54465 




DV1S0 

800617 
800816 
800819 
101'20 


1766872 
1669044 
1669045 


40028 

40019 
40039 
40020 
40021 


FD2 XDM 
FD2-2560 

FH2 32D 


FD-20 


743-0 

743-0/256 

743-0/512 

743-0/1024 

743-32 


S A ISO 
S'A 151 


15103 

15101 
15100 
15102 
1512S 


00 34-4001 

0034 4026 
0034 4015 
0034 4006 

0032 4000 


F 14411 IX 
F14S111X 
FI47I1IX 
F34A411X 
F34A611X 


76S6-K 

7659 K 
7861 K 


425602 
42S612 
425622 
425322 




FieiMMe Dtec FO 
Mimwn 651 or Equiv 


FO VI (Vinyl JecKetl 


30712003 


2.95 


- 


4706S1 


- 


CMF31 


FOIV 


- 


40002 


- 


FO 165 


511-0 


- 


ISO 26 


F 065 1000 


F61A111X 


7910 


- 




MM FleilMe Dlec 1 ■ 

V. Single Headed 

Drives 
Single Density M«d>4 


Soli Sector (Unformatted) 

10 Hard Sector 

16 Hard Sector 

Son Sector lUnformanedl W'Hub Ring 

10 Hard Sector w'Hub Ring 

16 Hard Sector * Hub Ring 


3401 
3403 
340S 
3431 
3433 
3435 


1.99 
1 99 

1 99 
2.19 

2 19 
2.19 


- 


475001 
4/5010 
475016 


54256 

5425 7 
54256 


- 


104/1 
107/1 
105/1 


- 


40500 
4050 1 
40 502 


M01 

MH1 


MO 1 
MO 110 
MO 116 


744-0 
744 10 
744 16 


S A 104 
S'A 107 
S/A-106 


15300 
15325 
15326 


M052S-01 
MO52S-10 
M0S2S-16 
M0S2S 01 
M0S2S 10 
M0S2S 16 


M11A211X 
M41A211X 
MS1A211X 


7897 
'898 

7899 


441002 
441102 
441162 




MM FKilM DMc Id 

5 a Single Heeded 

Drives 
Double Density Madia 


Son Sector 
10 Hard Sector 
16 Hard Sector 


3417 
3418 
3419 


2.24 
2.24 
224 


_ 


- 


54646 
54649 
54652 


- 


104/10 
107/10 
IOS'10 


- 


- 


- 


- 


- 


- 


- 


M0540 01 
M0540 10 

M0S40 16 


- 


- 


-_ 




Mini Fteiibte Otoe 2d 
•s . OoubM Headed 
Drives 
1 Double Oenaity Medie 


Son Sector 
10 Hard Sector 
16 Hard Sector 


14." 

3423 
3425 


2.74 
274 
2.74 


- 


- 


54624 
54627 
54630 


- 


104/20 
107/20 
105/20 


- 


- 


M02 
MH2 


- 


745-0 
745-10 
745 16 


S'A 154 
S A 157 
S'A 155 


- 


MD550 01 
M0550 10 
MOSSO-16 


- 


- 


- 


/ 



Memorex Flexible Discs.. .The Ultimate in Memory Excellence 



Ml MBit 



Quality 

Memorex means quality products that you can depend on. 
Quality control at Memorex means starting with the best 
materials available. Continual surveillance throughout the 
entire manufacturing process. The benefit of Memorex's years 
of experience in magnetic media production, resulting, for 
instance, in proprietary coating formulations. The most sophis- 
ticated testing procedures you'll find anywhere in the business. 

100 Percent Error Free 

Each and every Memorex Flexible Disc is certified to be 100 
percent error free. Each track of each flexible disc is tested, 
individually, to Memorex's stringent standards of excellence. 
They test signal amplitude, resolution, low-pass modulation, 
overwrite, missing pulse error and extra pulse error. They are 
torque-tested, and competitively tested on drives available 
from almost every major drive manufacturer in the industry 
including drives that Memorex manufacturers. Rigid quality 
audits are built into every step of the manufacturing process 
and stringent testing result in a standard of excellence that 
assures you, our customer, of a quality product designed for 
increased data reliability and consistent top performance. 

Customer-Oriented Packaging 

Memorex's commitment to excellence does not stop with a 
quality product. They are proud of their flexible discs and they 
package them with pride. Both their packaging and their 
labeling have been designed with your ease of identification 
and use in mind. The desk-top box containing ten discs is 
convenient for filing and storage. Both box labels and jacket 
labels provide full information on compatibility, density, sec- 
toring, and record length. Envelopes with multi-language care 
and handling instructions and color-coded removable labels 
are included. A write-protect feature is available to provide 
data security 

Full One Year Warranty — Your Assurance of Quality 

Memorex Flexible Discs will be replaced free of charge by 
Memorex if they are found to be defective in materials or 
workmanship within one year of the date of purchase. Other 
than replacement, Memorex will not be responsible for any 
damages or losses (including consequential damages) caused 
by the use of Memorex Flexible Discs. 



Quantity Discounts Available 

Memorex Flexible Discs are packed 10 discs to a carton and 
10 cartons to a case. Please order only in increments of 100 
units for quantity 100 pricing. We are also willing to accom- 
modate your smaller orders. Quantities less than 1 00 units are 
available in increments of 10 units at a 10% surcharge. 
Quantity discounts are also available. Order 500 or more 
discs at the same time and deduct 1%; 1 ,000 or more saves 
you 2%; 2,000 or more saves you 3%; 5,000 or more saves you 
5%; 1 0,000 or more saves you 7%; 25,000 or more saves you 
8%; 50,000 or more saves you 9% and 100,000 or more discs 
earns you a 1 0% discount off our super low quantity 1 00 price. 
Almost all Memorex Flexible Discs are immediately available 
from CE. Our warehouse facilities are equipped to help us get 
you the quality product you need, when you need it. If you need 
further assistance to find the flexible disc that's right for you, 
call the Memorex compatibility hotline. Dial 800-538-8080 
and ask for the flexible disc hotline extension 0997. In California 
dial 800-672-3525 extension 0997. 

Buy with Confidence 

To get the fastest delivery from CE of your Memorex Flexible Discs, 
send or phone your order directly to our Computer Products 
Division. Be sure to calculate your price using the CE prices in this 
ad. Michigan residents please add 4% sales tax. Written purchase 
orders are accepted from approved government agencies and 
most well rated firms at a 1 0% surcharge for net 1 billing. All sales 
are subject to availability. All sales are final. Prices, terms and 
specifications are subject to change without notice. Out of stock 
items will be placed on backorder automatically unless CE is 
instructed differently. International orders are invited with a $20.00 
surcharge for special handling in addition to shipping charges. All 
shipments are F.O.B. Ann Arbor, Michigan. No COD's please. Non- 
certified and foreign checks require bank clearance. 

Mail orders to: Communications Electronics, Box 1002, Ann 
Arbor, Michigan 48106 USA. Add $8.00 percase or partial-case of 
100 8-inch discs or $6.00 per case of 100 5 1 /4-inch mini-discs for 
U.P.S. ground shipping and handling in the continental U.S.A. If you 
have a Master Charge or Visa card, you may call anytime and place 
a credit card order. Order toll-free in the United States. Call 
anytime 800-521-4414. If you are outside the U.S. or in Michigan, 
dial 313-994-4444. Dealer inquiries invited All order lines at 
Communications Electronics are staffed 24 hours. 
Copyright 1981 Communications Electronics" 




svacesa eaniiextttei.iiei 




VISA 



taster charge 1 



Order Toll-Free! 
(800)521-4414 




For Data Reliability— Memorex Flexible Discs 




TM 



COMMUNICATIONS 
ELECTRONICS" 



^376 



Computer Products Division 

854 Phoenix D Box 1 002 D Ann Arbor, Michigan 48 1 06 U.S.A. 
Call TOLL-FREE (BOO) 521 -441 4 or outside U.S.A. (31 3) 994-4444 



INTELLIGENT VIDEO I/O FOR S-100 BUS 




VIO-X 

The VIO-X Video I/O Interface for the 
S-100 bus provides features equal to most 
intelligent terminals both efficiently and 
economically. It allows the use of standard 
keyboards and CRT monitors in conjunc- 
tion with existing hardware and software. It 
will operate with no additional overhead in 
S-100 systems regardless of processor or 
system speed. 

Through the use of the Intel 8275 CRT 
controller with an onboard 8085 processor 
and 4k memory, the VIO-X interface oper- 
ates independently of the host system and 
communicates via two ports, thus elimi- 
nating the need for host memory space. 
The screen display rate is effectively 80,000 
baud. 

The VIO-X1 provides an 80 character by 
25 line format (24 lines plus status line) 
using a 5 x 7 character set in a 7 x 10 dot 
matrix to display the full upper and lower 
case ASCII alphanumeric 96 printable 
character set (including true descenders) 
with 32 special characters for escape and 
control characters. An optional 2732 
character generator is available which 
allows an alternate 7 x 10 contiguous 
graphics character set. 




FULCRUM 

COMPUTER PRODUCTS 



M 



Distributed by 



The VIO-X2 also offers an 80 character 
by 25 line format but uses a 7 x 7 character 
set in a 9 x 10 dot matrix allowing high- 
resolution characters to be used. This 
model also includes expanded firmware for 
block mode editing and light pen location. 
Contiguous graphics characters are not 
supported. 

Both models support a full set of control 
characters and escape sequences, includ- 
ing controls for video attributes, cursor 
location and positioning, cursor toggle, 
and scroll speed. An onboard Real Time 
Clock (RTC) is displayed in the status line 
and may be read or set from the host 
system. A checksum test is performed on 
power-up on the firmware EPROM. 

Video attributes provided by the 
8275 in the VIO-X include: 

• FLASH CHARACTER 

• INVERSE CHARACTER 

• UNDERLINE CHARACTER or 

• ALT. CHARACTER SET 

• DIM CHARACTER 

The above functions may be toggled 
together or separately. 

The board may be addressed at any port 
pair in the IEEE 696 (S-100) host system. 
Status and data ports may be swapped if 
necessary. Inputs are provided for parallel 
keyboard and for light pen as well as an 
output for audio signalling. The interrupt 
structure is completely compatible with 
Digital Research's MP/M ®. 

^285 



Additional features include. 

HIGH SPEED OPERATION 

PORT MAPPED IEEE S-100 

INTERFACE 

FORWARD/REVERSE SCROLL or 

PROTECTED SCREEN FIELDS 

CONVERSATIONAL or BLOCK 

MODE (opt) 

INTERRUPT OPERATION 

CUSTOM CHARACTER SET 

CONTROL CHARACTERS 

ESCAPE CHARACTER 

COMMANDS 

INTELLIGENT TERMINAL 

EMULATION 

TWO PAGE SCREEN MEMORY 



VIO-X1 - 80 x 25 5 X7 A & T $295.00 

Conversational Mode 
VIO-X2 -80X25 7X7A&T $345.00 

Conversational & Block Modes 



CZ3 



J_L 



VIOX S 100 I/O INTERFACE 



WW COMPONENT SUPPLY INC. 1771JUNCTION AVENUE • SAN JOSE, CA 951 12 • (408)295-7171 



^See List of Advertisers on page 194 



Microcomputing, August 1981 187 



DIGITAL RESEARCH COMPUTERS 

(214) 271-3538 



32K S-100 EPROM CARD 
NEW! 




$79.95 

KIT 



USES 2716s 

Blank PC Board - $34 

ASSEMBLED & TESTED 
ADD $30 

SPECIAL: 2716 EPROM s (450 NS) Are $9.95 Ea. With Above Kit. 



KIT FEATURES: 

1 Uses +5V only 2716 (2Kx8) EPROMs 

2 Allows up to 32K of software on line! 

3 IEEE S-100 Compatible 

4. Addressable as two independent 16K 

blocks 
5 Cromemco extended or Northstar bank 

select 
6. On board wait state circuitry if needed 



11 



Any or all EPROM locations can be 

disabled. 

Double sided PC board, solder-masked, 

silk-screened 

Gold plated contact fingers 

Unselected EPROMs automatically 

powered down for low power. 

Fully buffered and bypassed. 



32K SS-50 RAM 



$ 329 



00 



KIT 



For 2MHZ 
Add $10 



Blank PC Board 
$50 



For SWTPC 
6800 - 6809 Buss 



12. Easy and quick to assemble. 



Support IC's 

and Caps 

$19.95 

Complete Socket Set 

$21.00 



Fully Assembled, 

Tested, Burned In 

Add $30 



At Last! An affordable 32K Static RAM with full 
6809 Capability. 

FEATURES: 

1. Uses proven low power 2114 Static RAMS. 

2. Supports SS50C - EXTENDED ADDRESSING. 

3. All parts and sockets included. 

4. Dip Switch address select as a 32K block. 

5. Extended addressing can be disabled. 

6. Works with all existing 6800 SS50 systems. 

7. Fully bypassed. PC Board is double sided, 
plated thru, with silk screen. 



16K STATIC RAM KIT-S 100 BUSS 



PRICE CUT! 



$ 1 69 9 ?, T 




jk ~^t tak m "^ - "■ — — -- 



i ii ii muni in 
ill i iiii i II i it ii 



PRICE CUT! 



BLANK PC BOARD W/DATA-$33 

LOW PROFILE SOCKET SET-$12 

SUPPORT IC'S & CAPS-$19.95 



KIT FEATURES ..-....^imuiimmm.H 

1 Addressable as four separate 4K Blocks 
2. ON BOARD BANK SELECT circuitry. (Cro- 
memco Standard'). Allows up to 512K on line! 
3 Uses 2114 (450NS) 4K Static Rams. 

4. ON BOARD SELECTABLE WAIT STATES 

5. Double sided PC Board, with solder mask and 
silk screened layout. Gold plated contact fingers 
6 All address and data lines fully buffered ASSEMBLED & TESTED-ADD $35 
7. Kit includes ALL parts and sockets 

8 PHANTOM is jumpered to PIN 67 
9. LOW POWER: under 1.5 amps TYPICAL from 
the +8 Volt Buss 

10 Blank PC Board can be populated as any 
multiple of 4K. 



OUR #1 SELLING 
RAM BOARD! 



16K STATIC RAM SS-50 BUSS 



I x ' r ;' t &Ffa i & i 



UlilSlSlllIIIIl 
IIIIIIEIIIIII 



$159 



KIT 



FULLY STATIC! 



FOR 2MHZ 
ADD $10 



ajff jajt gfe • 



Hi 



FOR SWTPC 
6800 BUSS! 



ASSEMBLED AND 
TESTED - $35 



KIT FEATURES: 

1. Addressable on 16K Boundaries 

2 Uses 2114 Static Ram 

3. Fully Bypassed 

4 Double sided PC Board Solder mask 
and silk screened layout 

5 All Parts and Sockets included 

6 Low Power Under 15 Amps Typical 



BLANK PC BOARD— $35 COMPLETE SOCKET SET— $12 

SUPPORT IC'S AND CAPS— $19.95 



H e*fl STEREO! Nfy, 

S-100 SOUND COMPUTER BOARD 



COMPLETE KIT! 
$g495 

(WITH DATA MANUAL) 



BLANK PC 

BOARD W/DATA 

$31 



At last, an S-100 Board that unleashes the full power of two 
unbelievable General lnstrumentsAY3-8910NMOS computer 
sound IC's. Allows you under total computer control to 
generate an infinite number of special sound effects for 
games or any other program Sounds can be called in BASIC, 
ASSEMBLY LANGUAGE, etc. , 

KIT FEATURES: 

* TWO Gl SOUND COMPUTER IC'S 

* FOUR PARALLEL I/O PORTS ON BOARD. 

* USES ON BOARD AUDIO AMPS OR YOUR STEREO. 

* ON BOARD PROTO TYPING AREA 

* ALL SOCKETS, PARTS AND HARDWARE ARE INCLUDED 

* PC BOARD IS SOLDERMASKED, SILK SCREENED, WITH GOLD CONTACTS. 

* EASY, QUICK, AND FUN TO BUILD. WITH FULL INSTRUCTIONS. 

* USES PROGRAMMED I/O FOR MAXIMUM SYSTEM FLEXIBILITY. 
Both Basic and Assembly Language Programming examples are included. 

SOFTWARE: 

SCL T " is now available! Our Sound Command Language makes writing Sound Effects programs 
a SNAPt SCL T "also includes routines for Register-Examine-Modify, Memory-Examine-Modify, 
and Play-Memory. SCL™ is available on CP/M* compatible diskette or 2708 or 2716. Diskette - 
$24.95 2708 - $19.95 2716 - $29.95. Diskette includes the source. EPROMS are ORG at 
E000H 

4K STATIC RAM 

National Semi. MM5257. Arranged 4K x 1. +5V, 18 PIN DIP. A 
Lower Power, Plug in Replacement for TMS 4044. 450 NS. 
Several Boards on the Market Will Accept These Rams. SUPER 
SURPLUS PURCHASE! PRIME NEW UNITS! 

8 for $16 32 for $59.95 



SPECIAL PURCHASE! 

UART SALE! 

TR1602B — SAME AS TMS601 1, 
AY5-1 01 3, ETC. 40 PIN DIP 



TR1602B 



EACH 



4For $ 10 



00 



CRT CONTROLLER CHIP 
SMC #CRT 5037. PROGRAMMABLE FOR 80 x 24, ETC. VERY RARE 
SURPLUS FIND. WITH PIN OUT. $12.95 EACH. 



NEW! G.I. COMPUTER SOUND CHIP 

AY3-8910 As featured in July, 1979 BYTE! A fantastically powerful Sound & Music 
Generator. Perfect for use with any 8 Bit Microprocessor Contains 3 Tone Channels. 
Noise Generator, 3 Channels of Amplitude Control 16 bit Envelope Period Control, 2-8 
Bit Parallel I/O 3 D to A Converters, plus much more! All in one 40 Pin DIP Super easy 
interface to the S-100 or other busses $11.95 PRICE CUT! 

SPECIAL OFFER: $ 1 4 . 95 each Add $3 for 60 page Data Manual. 



Digital Research Computers 

w (OF TEXAS) " 

P.O. BOX 401565 • GARLAND, TEXAS 75040 • (214) 271-3538 



TERMS: Add $2.00 postage. We pay balance Orders under $15 add 75C 
handling. No C.O.D. We accept Visa and MasterCharge. Tex. Res. add 5% 
Tax. Foreign orders (except Canada) add 20% P & H. Orders over $50, add 
85C for insurance. 



•TRADEMARK OF DIGITAL RESEARCH. 



WE ARE NOT ASSOCIATED WITH DIGITAL RESEARCH OF CALIFORNIA, THE SUPPLIERS OF CPM SOFTWARE. 




"THE BIG BOARD 

OEM - INDUSTRIAL - BUSINESS - SCIENTIFIC 

SINGLE BOARD COMPUTER KIT! 

Z-80 CPU! 64K RAM! 




</) 



__ <D O 
O =LO 
UJ <0^ 

ffl c-o 

2 ;;< 

UJ ~-q 
< OT3 




******* 






♦>-*»-«^^%', 





E*«fi!!'fc&-*3 



«%♦•* 



« 



■,*;;;*;%♦:%;;;>,;>>;%•;«;♦;♦:♦:*;♦;.;■ 



THE FERGUSON PROJECT: Three years in the works, and maybe too good to be true. A tribute to hard headed, 
no compromise, high performance, American engineering! The Big Board gives you all the most needed 
computing features on one board at a very reasonable cost. The Big Board was designed from scratch to run the 
latest version of CP/M*. Just imagine all the off-the-shelf software that can be run on the Big Board without any 
modifications needed! Take a Big Board, add a couple of 8 inch disc drives, power supply, an enclosure, C.R.T., 
and you have a total Business System for about 1/3 the cost you might expect to pay. 



$ 649 .? 



(64K KIT 
BASIC I/O) 



FULLY SOCKETED! 



FEATURES: (Remember, all this on one board!) 



SIZE: 872 x 13% IN. 
SAME AS AN 8 IN. DRIVE. 
REQUIRES: • 5V @ 3 AMPS 
♦ - 12V @ .5 AMPS. 



64K RAM 



24 x 80 CHARACTER VIDEO 



Uses industry standard 4116 RAM'S. All 64K is available to the user, our VIDEO 
and EPROM sections do not make holes in system RAM. Also, very special care 
was taken in the RAM array PC layout to eliminate potential noise and glitches. 



Z-80 CPU 



With a crisp, flicker-free display that looks extremely sharp even on small 
monitors. Hardware scroll and full cursor control. Composite video or split video 
and sync. Character set is supplied on a 2716 style ROM, making customized 
fonts easy. Sync pulses can be any desired length or polarity. Video may be 
inverted or true. 5x7 Matrix - Upper & Lower Case 



Running at 2.5 MHZ. Handles all 4116 RAM refresh and supports Mode 2 
INTERUPTS. Fully buffered and runs 8080 software. 



FLOPPY DISC CONTROLLER 



SERIAL I/O (OPTIONAL) 



Full 2 channels using the Z80 SIO and the SMC 8116 Baud Rate Generator. FULL 
RS232 For synchronous or asynchronous communication. In synchronous 
mode, the clocks can be transmitted or received by a modem. Both channels can 
be set up for either data-communication or data-terminals. Supports mode 2 Int. 
Price for all parts and connectors: $85. 



Uses WD1771 controller chip with a TTL Data Separator for enhanced 
reliability. IBM 3740 compatible. Supports up to four 8 inch disc drives Directly 
compatible with standard Shugart drives such as the SA800 or SA801 . Drives can 
be configured for remote AC off-on. Runs CP/M* 2.2. 



TWO PORT PARALLEL I/O (OPTIONAL) 



Uses Z-80 PIO. Full 16 bits, fully buffered, bi-directional. User selectable hand 
shake polarity. Set of all parts and connectors for parallel I/O: $29.95 



BASIC I/O 



Consists of a separate parallel port (Z80 PIO) for use with an ASCII encoded 
keyboard for input. Output would be on the 80 x 24 Video Display. 



REAL TIME CLOCK (OPTIONAL) 



Uses Z-80 CTC. 
parts: $14.95 



Can be configured as a Counter on Real Time Clock. Set of al 



SYSTEM COMPARISON 



64K RAM KIT $370.00 

80 x 24 Video Kit 365.00 

Floppy Disk Controller Kit 235.00 

Z-80 CPU Kit 185.95 

SER A PAR. I/O 129.95 

S-100 Mother Board 45.00 

SUB TOTAL $1330.90 



Talk about bangs per buck! The prices shown for 
S100 kits were taken from the July 1980 BYTE. 
This will give some basis for comparison between 
the Big Board and a similar system implementa- 
tion on the S100 Buss. 



CP/M* 2.2 FOR BIG BOARD 



The popular CP/M* D.O.S. modified by MICRONiX 
SYSTEMS to run on Big Board is available for $150.00. 



PC BOARD 



Blank PC Board with Rom Set and Full Documentation. 

$199.00 



PFM 3.0 2K SYSTEM MONITOR 



The real power of the Big Board lies in its PFM 3.0 on board monitor. PFM commands include: Dump Memory, Boot CP/M*, Copy, Examine, Fill Memory, Test Memory, Go To. 
Read and Write I/O Ports, Disc Read (Drive, Track, Sector), and Search. PFM occupies one of the four 2716 EPROM locations provided. 
Z-80 is a Trademark of Zilog. 



Digital Research Computers 

w (OF TEXAS) r 

P.O. BOX 401565 • GARLAND, TEXAS 75040 • (214) 271-3538 



TERMS: Shipments will be made approximately 3 to 6 weeks after we 
receive your order. VISA, MC, cash accepted. We will accept COD's (for the 
Big Board only) with a $75 deposit. Balance UPS COD. Add $3 OOshipping 



TRADEMARK OF DIGITAL RESEARCH. 



NOT ASSOCIATED WITH DIGITAL RESEARCH OF CALIFORNIA, THE ORIGINATORS OF CPM SOFTWARE 
**1 TO 4 PIECE DOMESTIC USA PRICE. 




Logic Probe Kit. 
■ $1795 



APPLE CARDSf APPLE 1 1 PIUS 



» 



Compliti aasy-to- 
follow instruction* 
help make thi» • 
ona-night pro|*ct 



'124' 



BUY 5 FOR *16. 15 each 



77 



LS' Super 

*SALE* 



744.SOO 


26 


74LS155 


74LS02 


26 


74LS156 


74LS03 


26 


74LS160 


74LS04 


26 


74LS161 


74LSOS 


28 


74LS162 


74LS09 


26 


74LS163 


74LS10 


.26 


74LS164 


74LS20 


26 


74LS165 


74LS21 


28 


744.S170 


74LS22 


26 


74LS174 


74LS26 


.49 


74LS175 


74LS27 


26 


74LS190 


74LS30 


28 


74LS193 


74LS32 


22 


74LS195 


74LS38 


32 


74LS198 


74LS4 2 


65 


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74LS48 


.78 


74LS240 


74LS51 


25 


74LS241 



74LS54 

74LS74 

74LS7 5 

74LS83 

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74LS86 

74LS90 

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744.S107 

74LS112 

74LS113 

74LS122 

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74LS153 



35 
38 

80 



69 



74LS243 


145 


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145 


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225 


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95 


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74LS258 


95 


74LS2S9 


285 


74LS279 


44 


74LS283 


100 


74LS293 


185 


74LS298 


120 


74LS366 


95 


74LS367 


55 


MLS 368 


55 


74LS373 


1.39 


74LS374 


139 


74LS386 


65 



TO -3 citf 

1 5 AMPS 
5V0LTS 



SERIAL— 1,5910 
PARALLEL _^$ QQ|1 
INTEGER «r $ _ 

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system 425« 

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ISM5832 MICROPROCESSOR REAL-TIME 

:lock/ calendar 

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90 -- «•• *• « 1 . 

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•lobal Spscialtias 

Logic Probes 



48k-*AV 
64k-hZ 

W/ PURCHASE OF 
APPLE RECEIVE 
SPECIAL PRICING: 

BASE II PRIITER— *$!$■•• 
0lSKIIi/ciil.-^ $ 595.M 
OlSKIIt/ltMl.— M35.M ' • ^ 
SUPR'IOOH — *W* % &' 
MIIITir.BiW 4*jJ^.> 

12 - 12MHz. — «125P V 
IITEGER BASIC 

CIH-»-»tmBB 



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*365°o 13' 



Green 
12 inch. 

*I55°° 




LP1 




2716 8 50ea 

5V450NS 



8 for 7.50ea 



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2102A .65<t 

1kx1 RAM 



NO Surois ir imirfiruciM 

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turns an ordinary 

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r Mjr Mfxci •• - * 

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0*0 *«««* «».«••.*«- 



>40.oo 



♦79.50 



LP3 



*> t»tl*««l ' 
I .**> *» t" tod 




|2708 
450NS 

12732 



4 75ea 8 for 4. 
25.50ea 4 for 21.50ea 



' | -.* 

* ■ J 



boxe_ inc. 



New for the 



UPD4U-2 

4k x1 RAM j; 

MICROSOF 

16K RAM 
CARD 



AY5-1013A %o 95 

30K Band UART •*-'~' 

4116-300NS. ^2.25 

16k x1 RAM 

8/*16.00 



ea 



IC SOCKETS 


8 PIN 10/1.20 


14 


10/1.40 


16 


10/160 


18 


10/1.90 


20 


10/2 80 


22 


10/2.80 


24 


10/2 80 


28 


10/3.80 


[40 


10/4.75 



** n 59.95 



S100^AE 

rWTK 
RM 



^-^ 



«« WW MOWMMlI 

tM'ttmo mmtmr momt 
mt'S in **o*>$*o 

S OO IOMI fr«MO«MOS| 
4 <JM/ C0* mtrio* 



|4116 300NS 3.00ea 8 for 19.50 
200NS 3.75ea 8 for 24.50 

|2114L 300NS 3.65 ea 4 for 13.95 
200NS 4 OOea 4 for 14.95 



2 80 8.95 

Z-80ACTC 12.50 

Z-80ACPU 12.50 

Z -80 002 16-64K 129.00 

8085A 11*50 

2901A 12.50 

MC6800 9.50 



ASSiMttfO 
ATESTEO 



*269. 



ATARI® 800™ 
COMPUTER SYSTEM 

'OOCiaHUflK— HI9.00 
(OOClBMlll 18K — — *H3 00 

*«300 COMPUTER 

Best Buy' 

ATARI PERIPHERALS: 

Pnnllite) % mm Pi »Ur('w) *379 00 




VISICALC 

1 APPLE— 

ATARI — 



<< 



» 



1981 

129.I/.C Master 



Apple Expansion Kit 
16K Memory Add -On 
Includes Instructions 

Ml! 



B8264-20 w u "-»oq 

^..Iv- -" «iiru;'.J29, 



2051 

EAROM 



P8155 



"ALLOW ZWKS. DEl'T IF 
PERSMUL CHECK IS SEIT. 



CONCORD 



^297 



lieu lii HhM 

lntirfici(85o)'l.5.00 
MMb bimj 

Star Rudirs l 49 00 
Suci liuNrt t|/N 
Clltt S 3Z 00 
KMIM >1200 
HliOM $ 1?00 
Blicinti <I2II 



Dill Drill , 5G500 
MM! '1(9.00 

Jiyslicks l U00 



Assiallir Editif 
Music CiRpisir 
Muling List 
TV Switch Bn 

I6K RAM 
8K RAM 



•49 00 
*49 00 
'WOB 
$ 895 

$ 15500 
•119.00 



1971 SO. STATE COLLEGE 
ANAHEIM, CALIF. 92806 



CHECK-- M/O 
NO COD 
*10.MIN ORDER/ CA RES ADD 6% 



2102 

450NS 
8038 
NE555 
AY5-1013A 
1488 
1489 
8T26 
8T28 
8212 
8216 
IS4106CR 
IT410TRIAC 
7905 
7908 
7915 
7918 
7805 
7806 
7808 
7812 
MC1330A1P 

MC1358P 

LM380 

LM565N 

LM741 

MC1458P 

LM720 



TRS80 
16K Add -On 
Instruct ions A 
[Dip Switches 
$25.95 



5712 




*' 



'v 



-"**<> 



Sh»n 



572 




1 . 



1459° *155°° 

Description 

' ■ . RS 2 3 2C Compottbla Digital Tranatar 

Switch s designed ios*'ici Tiodems 
Delweei ttontend p'oce»so»s An?4pinsol 
the connerlor *re smutched with Pm I Mn'ed 
to ground 



Tbar 



INCORPORATED 



190 Microcomputing, August 1981 



WAMECO 

THE COMPLETE PC BOARD HOUSE 
EVERYTHING FOR THE S-100 BUSS 



•* CPU-2 Z80 PROCESSOR BOARD ON BOARD ROM 
AND HARDWARE POWER ON JUMP. 
PCBD $35.95 KIT $135.95 

•* MEM-3 24 ADDRESS LINES EXPANDABLE IN 1K 
INCR. ADDRESSABLE IN 8K BLOCKS. BIDIREC- 
TIONAL BUSSING. 



PCBD $ 42.95 

KIT WITH 2114L-4 $475.95 
A&T WITH 2114L-4 $505.95 



KIT LESS RAM . . . $119.95 
KIT WITH 2114L-2 $549.95 
A&T WITH 2114L-2 $579.95 



■* FPB-1A FRONT PANEL BOARD FOR 8080A AND Z80 
SYSTEMS IMSAI COMPATIBLE. 
PCBD $56.95 KIT $1 75.00 

•* MEM-2 16K RAM 2114's. ADDRESSABLE IN 4K 
BOUNDARIES. 
PCBD .... $33.95 KIT (LESS RAMS) .... $80.95 

•* EPM-2 16/32K ROM USES 2716 OR 2708. ADDRESS- 
ABLE IN 4K BOUNDARIES. 
PCBD .... $33.95 KIT (LESS ROMS) .... $74.95 



«* CPU-1 8080A PROCESSOR BOARD WITH VECTOR 
INTERRUPT. 
PCBD $33.95 KIT $124.95 

■* QMB-12 13 SLOT MOTHER BOARD. 

PCBD $42.95 KIT $1 25 .95 

*■ QMB-9 9 SLOT MOTHER BOARD. 

PCBD $35.95 KIT $1 09.95 

■* PTB-1 POWER SUPPLY AND TERMINATOR BOARD. 
PCBD $29.95 KIT $49.95 

*• RTC-1 REAL TIME CLOCK BOARD WITH TWO 
INTERRUPTS. 
PCBD $29.95 KIT $79.95 

«* MEM-1A 8K RAM, USES 2102's. 

PCBD $33.95 KIT (LESS RAM) $71.95 

¥r IOB-1 I/O BOARD. ONE SERIAL, TWO PARALLEL 
WITH CASSETTE. PCBD $33.95 

#• FDC-1 A FLOPPY DISC CONTROLLER BOARD USES 
1771. PCBD $45.95 



FUTURE PRODUCTS: 80 CHARACTER VIDEO BOARD. 

8 PARALLEL PORT I/O BOARD. 

DEALER INQUIRIES INVITED, UNIVERSITY DISCOUNTS AVAILABLE 

AT YOUR LOCAL DEALER 



wmc 



inc. 



WAMECO, INC., P.O. BOX 877 • EL GRANADA, CA 94018 • (415) 728-9114 




CALIFORNIA COMPUTER SYSTEMS 

stoo 

2032 32K STATIC RAM A&T. 

450 NSEC . $579 00. 300 NSEC $585 00. 200 NSEC $629 00 

2116 16K STATIC RAM A&T 

450 NSEC $285 00, 300 NSEC $289 00, 200 NSEC $329 00 

2065 64K DYNAMIC RAM A&T $548.95 

2200 S-100 MAIN FRAM A&T $379 95 

2422 FLOPPY DISC WITH CP/M 2.2" $329 95 

2802 6502 PROCESSOR A&T $282 95 

2810AZ80 CPU A& T $249 95 

2710A 4 SERIAL 1/0 A & T $291.95 

27I8A 2 SERIAL, 2 PARALLEL A&T $305 95 

2720A 4 PARALLEL A&T $214.95 

PROTO BOARDS WW $39 95, S0LDERTAIL $29 95 

lAPPLE PRODUCTS 

7114A 12K R0M/PR0M $68.50 

7424A CALENDAR/CLOCK $106.95 

7440A PROGRAMMABLE TIMER $98.50 

7470A A TO CONVERTER $105.95 

7490A GPIB (IE 488) INTERFACE $265.95 

7710A ASYNC SERIAL $12595 

7712A SYNC SERIAL $153.95 

7720A PARALLEL STANDARD $98.95 

77208 PARALLEL CENTRONICS $98.95 

78118 ARITHMETIC PROCESSOR W/DISC $342 95 

781 1C ARITHMETIC PROCESSOR W/R0M $342 95 

7500A WW BOARD $22 95 

7510A SOLDERTAIL BOARD $2395 

ISOFTWARE 

2610 CP/M-MACR0 ASSEMBLER ON DISK $76 95 

2620 CP/M "SYMBOLIC INSTRUCTION DEBUGGER. $64.25 

2630 CP/M'"TEXT F0RMATER $64.25 

2640 CP/M "BACKGROUND PRINT UTILITY $42.95 



OTHER CCS PRODUCTS ARE AVAILABLE. 
CALL FOR PRICE. 



SStV 



MICROCOMPUTER PRODUCTS 



SI 00 PRODUCTS 

CBIA 8080 PROCESSOR PCBD $32 95 

KIT $15595, A&T $215 95 

CI-2 280 PROCESSOR BOARD 

KIT $198 95, A&T $269 95 

VBIC 64 x 16 VIDEO, PCBD $32 95 

KIT $15395, A&T $19995 

¥82 64 x 16 VIDEO, PCBD $32 95 

KIT $175 95. A&T $234 95 



VB3 80 CHARACTER VIDEO 4MHZ 
KIT $345 95, A&T 

UPGRADE RAMS FOR VB-3 



$42595 
$4200 



104 2 PARALLEL 2 SERIAL. PCBD $32 95 

KIT $15595, A&T $194 95 

PI-1 2708, 2716 PROGRAMMER BOARD 

KIT $135 95, A&T $185 95 

MB-10 16K STATIC RAM 

KIT $299.95, A&T $339 95 

APPLE PRODUCTS 

A488 IEEE 488 INTERFACE $399 95 

AI0 SERIAL/PARALLEL INTERFACE 

KIT $125 95. A&T $15595 

ASI0 SERIAL I/O 

KIT $87 95. A&T $97 95 

API0 PARALLEL 10 

KIT (W/0 CABLES) $67 95, A&T(W/0 CABLES) $87 95 

OTHER SSM PRODUCTS ARE AVAILABLE. 
CALL FOR PRICES. 



mm 




MONDAY-FRIDAY, 8:00 TO 12:00, 1:00 TO 5 30 
THURSDAYS, 8 00 TO 9:00 P M 

(415)728-9121 
P.O. BOX 955 • EL GRANADA, CA 94018 

PLEASE SEND FOR IC, XIST0R AND COMPUTER PARTS LIST 



AUG. SPECIAL SALE 
ON PREPAID ORDERS 

(CHARGE CARDS AND C D OR P I0T AVAILABLE ON THESE OFFERS) 

MEM-3 KIT LESS RAM $89.95 

IOB-1 KIT S99.95 

™* JJiC j ne% WAMECO INC. 
BOARDS WITH MIKOS PARTS 



MEM-3 32K STATIC RAM, PCBD 

KIT LESS RAM $95 95 A&T 

CPU-2 Z80 PROCESSOR, PCBD 

KIT LESS ROM S109.95. A& T 

EPM-2 16K/32K EPROM, PCBD 

KIT LESS ROM . $65 95. A& T 

FPB-1 FRONT PANEL. PCBD 

KIT S144 95. A&T 

CPU-1 8080 PROCESSOR. PCBD 
KIT $89 95. A& T 

OMB-12 13 SLOT MOTHER BOARD. PCBD 
KIT $95 95, A&T 



S36 95 
$135 95 

$32.95 
S14995 

$32.95 
$99 95 

$48 50 
S184 95 

S29 95 
S129 95 

$3995 
$135 95 



OTHER WAMECO PRODUCTS ARE AVAILABLE 
CALL FOR PRICES 



MIKOS PARTS ASSORTMENTS ARE ALL FACTORY MARKED PARTS KITS INCLUDE 
ALL PARTS LISTED AS REQUIRED FOR THE COMPLETE KIT LESS PARTS LISTED 
ALL SOCKETS INCLUDED 

LARGE SELECTION OF LS Til AVAILABLE. 

PURCHASE $50.00 WORTH OF LS TTL AND GET 1 0% CREDIT 
TOWARD ADDITIONAL PURCHASES PREPAID ORDERS ONLY 



VISA or MASTERCHARGE Send account number interbank number expiration date 
and sign your order Approx postage will be added Check or money order will be sent 
post paid in U S It you are not a regular customer please use charge, cashier s check or 
postal money order Otherwise there will be a two-week delay lor checks to clear Calit 
residents add 6°c tax Money back 30-day guarantee We cannot accept returned iC's 
that have been soldered to Prices subiect to change without notice SI iIiImi »rOr 
SI. 50 itnlci rinnji •■ iriiri las* tin SI 0.00 



Microcomputing, August 1981 191 






EPSON MX^SO 
Now in stock! 

The MX-80 dot matrix printer. 
Unequalled Epson reliability. Has 
all the features of the MX-70 plus 
more power and extra functions 

CALLUS 

C-ITOH STAR WRITER LETTER 
QUALITY PRINTING FOR UNDER 
$2000!/This daisywheel printer 
gives high quality at a low price. 
25 cps. Parallel and serial inter- 
faces available. CALL 



NEC SPINWRITER FROM THE 
FIRST NAME IN LETTER QUALITY 
PRINTERS/ Compumart offers 
beautiful print quality with NEC 
Spinwriter Terminals We carry all 
models from RO THRU KSR WITH 
NUMERIC KEYPAD -55 10- 5530. All 
versions give unsurpassed hard 
copy output! CALL FOR PRICES 



NEW INTEGRAL DATA'S 560 
PRINTER/ All the exciting features 
of the 400 series plus 141/2" paper 
capacity. 132 col. graphics printer. 
IDS 445. Priced lower than the 440 
and equipped with a better print 
head. With & w/o graphics 
IDS 460. Features include corre- 
spondence quality printing, high 
resolution graphics. 

CALL FOR PRICES 




CENTRONICS PRINTERS 
3 SERIAL MODEL 737 

The closest thing to letter quality 

print for under $1000 

List $1045 SPECIAL $795. 

737-1 Parallel Interface 

List $995 SALE PRICE $695. 

PLUS EXCITING REBATE OFFER 
ON CENTRONICS PRINTERS. 

OMNI 610 PRINTER FROM TEXAS 
INSTRUMENTS CALL US 

The 820 RO PACKAGE includes 
machine mounted paper tray and 
cable. A compressed print option 
and device forms control are 
standard features. 
THE 820 KSR PACKAGE includes 
fully ASCII Keyboard plus all of the 
leatures of the RO 

CALL FOR PRICES 



CLEARANCE ZENITH COLOR 
VIDEO MONITOR $349 



SUPER SELLING TERMINALS FROM 
LEAR SIGLER/We have the follow- 
ing Lear Siegler terminals in stock 
at prices too low to print! Call for 
quotes. 

ADM-3A/Industry*s favorite dumb 
terminal for some very smart 
reasons/ 

ADM-3A + NEW from Lear Siegler. 
CALL! 

IT IS HERE! It is the new Intermedi- 
ate Terminal from Lear Siegler. 

CALL FOR DETAILS 



SANYO MONITORS AT LOW COM- 
PUMART PRICES/ Sanyo's new line 
of CRT data display monitors are 
designed for the display of alpha- 
numeric or graphic data. 
9"SANYOB/W $169. 

12" SANYO B/W CALL 

12" SANYO W/ 

GREEN SCREEN CALL 

1 3" SANYO COLOR CALL 




NEC COLOR MONITOR/RECEIVER 
HIGH RESOLUTION/ 

Composite video using BNC con- 
nectors. 8-Pin connector for VCR/ 
VTR video loop In/ Out and 
television reception. CALL US! 



Visit our giant 

ANN ARBOR STORE 

1250 North Main Street 
Ann Arbor Michigan 



FREE CATALOGS 



MICRO 



Our complete 
line of micro- 
computers, 
accessories 
and 
peripherals. 



DEC LSI-T1 



Systems config- 
ured and 
integrated 
with other 
manufacturers 
compatibles. 

Send for them! 




HP-41C CALCULATORS 
MEMORY MODULES for storing 
programs of up to 2000 lines of 
program memory. 
"EXTRA SMART" CARD READER. 
Records programs and data back 
onto blank magcards. 
THE PRINTER. Upper and lower 
case. High resolution plotting. Port- 
able thermal operation. 
APPLICATION MODULES 

CALL FOR PRICES ON ALL 



NEW SUPER 41-CV SYSTEMS with 

Quad RAMS built-in. Maximum 

memory on-board leaves slots 

open for Application Pacs and 

peripherals. 

+ CARD READER 

+ CARD READER + PRINTER 

QUAD RAMS equivalent to four 

Memory Modules all packed 

into one. CALL ON ALL 



MATROX PRODUCTS/Compumart 
stocks the complete line. 

CALL ON SPECS 

DEC LSl-11/Compumart now 
offers the entire product line. 
CALL FOR PRICES AND DELIVERY 



NOVATION CAT ACOUSTIC 
MODEM Answer Originate. 



CALL 



NEW! D-CAT Direct Connect 
Modemi from Novation. CALL 



"/ 




1 



^ v GILTRONIX RS 232 SWITCH/ 

The ultimate in flexibility. You can 
connect three peripherals to one 
computer or three computers to 
one peripheral. Switches the eight 
most important RS 232 signals. 

CALL ON PRICE 

DYSAN DISKETTES/Single side, 
single density. Hard or Soft Sector 

$5. ea. 

MEMOREX 3401s/5l/4 / disks $3.25 
/with hub ring for Apple $3.50 

MEMORY INTEGRATED CIRCUITS/ 

Call for quantity discounts when 
ordering over 50 units. CALL 

MOTOROLA 4116 (200 Nano- 
second Plastic) $4.50 



RM EXPANSION ACCESSORIES 
FOR AIM— 

CALL SPECS AND PRICES 



APPLE m IS IN STOCK/Apple HI 

Information Analyst Package— 
128K Apple III. Black and White 
Monitor 12", and information ana- 
lyst software. CALL 

TOP SOFTWARE PACKAGES FROM 
COMPUMART 



VISICALC/FOR APPLE/FOR HP/ 
FOR COMMODORE/FOR ATARI 



SOFTWARE FROM APPLE/ Apple 
Plot (the perfect graphic comple- 
ment for Visicalc/ Dow Jones News 
8c Quotes/ Apple Fortrom/ Apple 
Writer/ Pascal Language System/ 
Controller Business System CALL 



PERSONAL SOFTWARE/Visidex/ 
VisiTrend/VisiPlot/VisiTerm CALL 
MUSE/ Super Text CALL 




MOUNTAIN COMPUTER/ 

Expansion accessories for Apple/ 
Super Talker/The Music System/ 
ROM plus board with Keyboard 
filter/ ROM Writer/Clock Calen- 
dar/ AtoD and Dto A Converter/ 
Clock for Apple/CPS Multifunction 
Board CALL 



VIDEX/ Video Term (80 col. x 24 
line. 7x9 Matrix plug in compati- 
ble board for Apple II) w/wo 
graphics EPROM/SSM Serial 8c 
Parallel. Apple Interface/ ABT's 
Numeric Key Plan/ California 
Microcomputer Keyboard CALL 



VIC 2 O PERSONAL COMPUTER 
FROM COMMODORE 

$299. 



IMPORTANT ORDERING INFORMATION 

CALL 800 343-5504. in Massachusetts (617) 491-2700. phones open 
from 8:30 am to 700 p.m. Mon-Fri 1LOO am to 400 p.m. Sat. 
PO'fc Accepted from Dun 8c Bradstreet rated companies— shipment 



contingent upon receipts ol signed purchase order 
SALE PRICES^ Valid for month of magazine date only— all prices sub- 
ject to change without notice. Our Ann Arbor ietaH store is open 
1LOO a.m. to 700 p.m. Tues-Frt 10:00 a.m. to 500 p.m. on Saturdays 




$1895. 



SAVE OVER $200 ON OUR BEST 
SELLING APPLE SYSTEM/ System 
includes a 48K Apple II, Apple 
Disk. DOS 3.3 and Controller and a 
Sup R MOD RF Modulator. 

List $2209. 
EXCLUSIVE FOR THE APPLE: 
Magic Wand, Videx, Z-80 sortcard 
( Requires 48K Apple and disk). 

COMPLETE SYSTEM $925. 



APPLE ACCESSORIES 

CHOOSE FROM: Silentype Printer 
w/x lace/Light Pen/Easy Writer 
(80 col. needaVidex)/Clockior 
Apple 

FROM MICROSOFT 16K RAM 

Board/FORTRAN. 

FROM COMPUTER STATION: 

Hi-Res Dump tor 460 Printer. 





OUR APPLE INVENTORY IS COM- 
PLETE. WE'VE GOT IT ALL- 
CALL US FOR PRICES 



$4695. 



CRISP LETTER QUALITY OUTPUT 
UNSURPASSED EASE OF 
OPERATION 

This Compumart/Commodore 
system includes a COMMODORE 
6032 32K CPU, a 4040 DUAL DISK, 
a C-ITOH PRINTER and x/face and 
WOBDCRAFT80 (all cables in- 
cluded). List $5386. 
CALL FOR DETAILS AND 
LOW PRICES 

A COMPLETE SYSTEM: includes 
a DUAL DISK DRIVE TRACTOR 
PRINTER and an 80 COLUMN 
32K CPU. No interfaces needed. 
Cables included. List $3685. 

COMPUMART $3335. 
SAVE $200 ON COMMODORE 
ACCESSORIES WITH PURCHASE 
OF A 32K PET- SAVE $100 WITH A 
16K PET. 

CHOOSE FROM: 

Visicalc/Word Pro 4/Wordcraft 80/ 
Ozz the Information Wizzard/ 
Dow Jones Portfolio Mgmt System/ 
Assembler Development Package. 








Systems 



WW 



4b$> 



$4249. 



This Basic System from Hewlett- 
Packard includes HP-63/ROM 
DRAWER/MASS STORAGE ROM/ 
51/4" SINGLE MASTER FLEXIBLE 
DISK DRIVE/HP-IB INTERFACE 
MODULE/2 METER HP-IB CABLE. 

SAVE $400 ON HP-65 SERIES AC- 
CESSORIES WITH THE PURCHASE 

OFANHP-85. 

CHOOSE FROM: PERIPHERALS; 
Disk Drives to Graphics Plotters 
ENHANCEMENTS; Basic Training/ 
General Statistics/ Financial Deci- 
sion/Math/Linear Programming 
($#5 EA.) ACCESSORIES; Enhance- 
ment ROM's/ ROM drawer/Over- 
head Transparency Kit SUPPLIES; 
Plotter Pens/Tape Cartridges 
INTERFACE MODULES; HP- IB Inter- 
connect Cables/Serial (RS-232C) 
Interface Module. 



$795. 



FROM ROCKWELL 
Our AIM Starter System for Educa- 
tional 8c Laboratory use includes 
4K AIM/BASIC & ROM/ASSEMBLER 
8c ROM/POWER SUPPLY EG1 EN- 
CLOSURE/CRAIG TAPE RECORDER. 

ACCESSORIES FOR AIM STARTER: 

PL 65 High Level Language/ Paper 
for the Aim (roll)/ Rockwell's 4 slot 
Motherboard/ 

CALL 





WE ALSO CARRY RM EXPANSION 
ACCESSORIES FOR THE AIM-65 
CALL FOR SPECS AND PRICES 



WE CARRY EVERY PERIPHERAL 
MADE FOR THE HP-65. 

CALL US FOR PRICES 






800-343-5504 




IN MASS CALL 617-491-2700 




COMPUMART. 

65 Bent Street, Dept 128, 

PO Box 568, Cambridge, MA 02139 



From THE LEADER . . . 

We just might be the largest independent small systems dealer in the country. Here's why: 

COMPUMART has been serving the computer needs of industry since 1971. 

We stock, tor immediate shipment, only those products from the finest micro-computer 
manufacturers. 

And any product, except software, can be returned within 10 days for a full refund— even 
if you just change your mind. We also honor all manufacturers' warranties. Our expert 
technicians will service any product we sell. 

Call us for more information on products, product configuration and service. Our phones 
are open Monday thru Friday, 8:30 a.m. to 7:00 p.m. and Saturday 11=00 am. to 400 p.m 

We have a staff of highly knowledgeable sales people waiting to hear from you. and 
to help. Because service is what we're all about. 



Peterborough NH 03458 



>UTI 


NG " 



Reader Service Number 



-Page Reader Service N umber 



Page 



Reader Service Number 



Page 



121 

91 

232 

261 

478 

393 

311 

249 

56 

187 

477 

387 

• 

494 

471 

192 

193 

480 

96 

55 

468 

466 

490 

124 

469 

256 

79 

299 

271 

170 

28 

376 

395 

90 

43 

42 

147 

58 

320 

18 

120 

370 

341 

336 

362 

346 

36 

110 

283 

499 

105 

227 

176 

467 

6 

197 

297 

141 

• 

293 

210 

484 

63 

486 



342 

61 

212 

250 

• 

34 

87 

491 

474 

82 

93 

47 

• 

272 



A B Computers 143 

Aardvark Technical Services 137 

Aardvark Technical Services 210 

Ackerman Digital Systems, Inc 23 

Action- Research Northwest 214 

Adventure International 54, 55 

Alpha Byte Stores CHI 

American Software & Systems, Inc 153 

American Square Computers 199 

Ancie Labs 103 

Apple Computer, Inc 210 

Apple Orchard 129 

Applied Analytics 73 

Archives, Inc 204 

Allen Ashley 208 

Audio Video Systems 72 

Aurora Software 53 

Aurora Systems, Inc 212 

Automated Equipment 77 

Automated Simulations 49 

Automated Simulations 208 

The Avalon Hill Game Company 212 

Axiom Corporation 205 

B.T. Enterprises 202 

BAYSIK Speech 210 

The CPU Shop 125 

C&S Electronics Mart Ltd 148 

California Data Corp 170 

Cambridge Learning 102 

Chips & Dale 127 

Cleveland Consumer 63 

Communications Electronics 186 

Compstat 104 

CompuCover 43 

Compumart 192,193 

CompuPro 176 

CompuServe HI 

The Computer Answer 112 

Computer Case Company 66 

Computer Design Labs 21 

Computer Discount of America 62 

Computer Dynamics 171 

Computer Exchange 213 

The Computerist, Inc 200 

Computer Plus 113 

Computer Sales& Service 92 

Computer Shopper 133 

Computers, Peripherals Unltd 143 

The Computer Stop 121 

The Computer Stop 202 

The Computer Stop 203 

Computers Wholesale 120 

Computer Trader 167 

Computerware 210 

Computronics, Inc 157 

Compuware Corporation 166 

Concord Computer Products 190 

Custom Electronics 155 

Cybernetics, Inc 8 

D & N Micro Products 104 

Data Ed, Inc 27 

Data Wholesale Corp 200 

Davis Systems, Inc 66 

Digital Pathways, Inc 198 

Digital Research Computers 188,189 

Digital Research Parts 180 

Digital Research, Inc CIV 

Digital Systems Engineering 88 

Digital Systems Engineering 150 

Discount Software Group 50 

Dosware, Inc 102 

Dr. Daley 32 

Dwo Quong Fok Lok Sow 100 

E & L Instruments, Inc 201 

ESP Computer Resources 209 

Ecosoft 133 

Electronic Specialists 217 

Electronic Systems 177 

Electrovalue Industrial 167 



End-of-File 155 

Epson America 52 

Erickson Communications 14 

Essex Publishing 88 

Fessenden Computer Service 155 

Floppy Disk Service 29 

General Videotex Corp 23 

Gimix, Inc 1° 8 

Gimix, Inc 163 

Gimix, Inc 206 

Gqdbout Electronics I 76 

Grafix 206 

Hanley Engineering 81 

Happy Hands I 53 

Heath Company 34,35 

Hobby Robotics 85 

Human Engineered Software 206 

Image Computer Products 210 

Inmac 106 



339 

116 

254 

327 

131 

191 

392 

22 

301 

488 

42 

465 

5 

243 

236 

265 

33 

476 

223 

Instant Software 

400 

401 

403 

404 

75 

485 

77 

496 

264 

73 

235 

3 

126 

203 

180 

92 

48 

41 

• 

464 
247 
222 



Game Programs 221 

New Products 82 

Master Directory 222 

Climate Computer 215 

Programmer's Kit 163,164,166,167,168,171 

Instructional Development Systems 198 

Integrand Research Corp 46 

Interaction Systems, Inc 204 

Interactive Microware 206 

Interactive Structures 139 

Interlude 25 

Intertec Data Systems 3 

J R Inventory Company 67 

J.C. Datatron H2 

J. E.S. Graphics 46 

J. PC. Products 210 

Jade Computer Products 183,184,185 

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194 Microcomputing, August 1981 



READER 
SERVICE 

Please help us to bring you a better 
magazine — by answering these questions: 



L What Is your ag«? 
D A 25 or under 

□ B 26-35 
C 36-45 
D 46-60 

O E Over 60 

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' Under $20,000 

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5 over $50,000 

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Please specify 



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and/or Entertainment 
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Physician, etc.) 

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make the decisions on the purchase of 
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LETTERS TO THE EDITOR 






Force-feeding Education 

The "Remarks" in the May 1981 issue 
caught my interest. I, too, have fond 
memories of high school and things have 
changed. I see this clearly since I taught 
mathematics on an intermediate and 
secondary level for the New York City 
Board of Education for two years. I am 
now teaching Computer Programming 
(BASIC, FORTRAN IV, and Pascal) to 
high school juniors and seniors. 

You have outlined the problems in edu- 
cation well. The baby-sitting attitude in 
the public schools is abhorrent but true. I 
assure you, no one, teacher or otherwise, 
finds it particularly effective or reward- 
ing to force people to learn. 

We do have the responsibility of edu- 
cating. This is especially important for 
those students who spend their most crit- 
ical periods in grades one to 12. The 
question is how. I agree totally; the com- 
puter has come into education at a per- 
fect time, but I maintain some intense 
reservations about computer-aided in- 
struction which is teacher independent 
and home-based. 

The unfortunate result of a student 
body separated and detached in the 
learning process would be the stunting of 
emotional and personal development. If 
the elements of interaction and commu- 
nication are eliminated, the student may 
grow up feeling most comfortable only in 
front of a CRT. 

I don't believe that the result would be 
more motivated children. Look back on 
your experiences in college. Although I 
am speaking about students whose age 
level is between six and 18, there is an 
analogy that can be drawn. What made 
the accounting course so uppermost in 
your mind? Where or from whom did the 
excitment come from? Was an honest 
concern about and interest in the stu- 
dents on the part of the teacher an ingre- 
dient in that positive experience? 

I see a renaissance in education com- 
ing about. The advent of computer-aided 
Instruction is responsible for this turning 
point. I am doing extensive research in 
this area and have implemented in-ser- 
vice workshops encouraging the use of 
computers not only in mathematics and 
science, but in languages (using speech 
synthesizing), history and English. Sim- 
ulations and video disks will surely en- 
hance and increase the amount of infor- 
mation retained by the student. Some 
other techniques will involve "live" pho- 
tos and accurate graphics, along with 
background music and professional 
voice over-dubbing. 

All in all, we should not force educa- 
tion. 



Moving the students out of the schools 
will not ensure better behavior in society; 
it may only postpone and augment the 
problems in the long run. I firmly believe 
this, even after being assaulted twice in 
the public schools. Finally, with human 
example and intervention, these situa- 
tions can be encountered and averted as 
soon as possible. The choice rests on a 
joint, concerted effort, on the part of the 
parents and schools. 

One thing is for certain. With CAI, fur- 
ther developed systems, and more teach- 
ers involved in this progress, the renais- 
sance in education is coming of age, re- 
gardless of how much time it will take, or 
the pain in the undertaking. That is why I 
foresee better schools, more effective 
teachers, and a raised level of learning. I 
am looking forward to the advances to be 
made by both teachers and Instant Soft- 
ware. 

Paul S. Drago 
St. Raymond High School for Boys 

Bronx, NY 



Wayne Green Replies 

Your argument has merely proven my 
point. 

The teacher I had for accounting had 
showmanship. We didn't really get to 
talk with him much or ask questions . . . 
it was all enthusiasm on his part and ex- 
citement. I find a similar enthusiasm 
from shows such as Connections, Free- 
dom to Choose, etc. If we can get exciting 
people to put this stuff on video, using 
computers to match the speed of the 
teaching to the interest and intellect of 
the student, I think we would have a win- 
ner. 

Your letter was most interesting. It's 
good to hear from the trenches. 

Wayne Green 



Inexpensive Word Processing 

Craig Anderton ("In Search of the Pro- 
cessed Word," May 1981, p. 39) leaves 
the impression that a sophisticated word 
processing system, such as his, must 
cost at least $10,000. Not so. Couple the 
new Osborne I, including its double den- 
sity option, with one of several daisy- 
wheel printers selling for under $2000, 
and you have a roughly comparable sys- 
tem, including the same software, for un- 
der $4000. 

I'm writing this letter on a used TRS-80 
Mod I with Radio Shack's Daisywheel II 
printer operating under Scripsit en- 
hanced with Acorn's Superscript. The 
cost is again under $4000, including disk 



drives. I suspect professionally useful 
word processing systems need no longer 
be as prohibitively expensive as Mr. 
Anderton's. 

Stan Franklin 
Memphis, TN 

Response: 

Your claim that a $4000 Osborne- 
based system is equivalent to the system 
described in the article is stretching 
things. The Osborne can't do multi-user 
tasks (which mine has to, on occasion), 
nor is it easily expandable (I've upgraded 
my system several times since the article 
was written). 

Craig Anderton 
Redwood Valley, CA 



Osborne the Obnoxious? 

If "it was inevitable'' that the Osborne I 
microcomputer would become a reality, I 
suppose it was also inevitable that the 
product introduction would be accom- 
panied by a torrent of the usual self-right- 
eous pomposity from Adam Osborne. 
Clearly, Osborne has every right to hype 
his micro-screened computer, but why 
does he make your readers suffer through 
a diatribe against the rest of the industry 
before getting to the system's features? 
Are we expected to buy an Osborne I be- 
cause it can do something better than 
other systems on the market, or as sim- 
ply a vote of support for the manufactur- 
er's imagined "mandate"? Such "crust" 
deserves an award, but I haven't yet de- 
cided whether Mr. Osborne's complexion 
is better suited to a raspberry or a lemon 
pie! 

Jack Carlson 
Anaheim, CA 



Osborne makes good reading. How- 
ever, there is more to say about the Os- 
borne I microcomputer than appears in 
the May 1981 issue of Microcomputing. 

In size and weight the Osborne I is 
more similar to a portable sewing ma- 
chine than to a briefcase. A more attrac- 
tive package would be something like the 
HP-85 with a couple of the new Sony 
3-1/2 inch floppy disk drives. 

An 80-column external monitor will 
not be available for the Osborne I, but 
rather for a subsequent Osborne model. 

Although Osborne touts compatibility 
and excoriates other manufacturers for 
their unique hardware and software de- 
signs, the Osborne I has its own hardware 
incompatibilities. The video output will 
not drive the standard monitor: you must 

Microcomputing, August 1981 195 






buy a unique Osborne monitor if you 
want a larger external display. The Os- 
borne I printer interface is standard 
RS-232 (serial) or standard IEEE-488 
(parallel). RS-232 is fine for expensive let- 
ter-quality printers but the standard mi- 
crocomputer printer is a low-cost unit 
with a Centronics-compatible (not 
IEEE-488) parallel interface. The Cen- 
tronics-compatible parallel interface has 
become the de facto standard microcom- 
puter printer interface. IEEE-488 is an 
expensive parallel interface used prima- 
rily by industry in multiple instrument, 
control/measurement systems. Osborne 
espouses low cost hardware; he should 
have awarded himself a true White Ele- 
phant award for that IEEE-488 interface. 
Other than that it looks like a good deal. 

Robert C. Briggs 
Mountain View, CA 



The Letters Pour In 

We are receiving a colossal number of 
letters from people who read my article in 
your magazine (May 1981). They are 
coming in at the rate often to 20 per day. 
That beats anything generated by public- 
ity in any other magazine. 

Adam Osborne 
Hay ward, CA 

What else did you expect?— Editors. 



More on CBASIC2 

I'd like to make the following com- 
ments on the review of CBASIC2 by 
Bruce Evans in the May 1981 issue of Mi- 
crocomputing (p. 254). 

1 . I agree with and wish to emphasize 
his comments about CP/M's ED editor. It 
is absolutely the worst I have ever used, 
and I have used several. 

2. Evans must have never seen Micro- 
soft BASIC, if he thinks CBASIC2 is the 
most extensive version of BASIC. Their 
BASIC 80 is at least as extensive (but it 
sure chews up a chunk of core). 

3. Let me put one false statement to 
rest here and now. CBASIC2 does not 
run faster than the usual BASICs! The 
interpreter running on my TRS-80 Model 
I is faster! CBASIC2 is very slow, due to 
the fact (as Mr. Evans states) that it is not 
a true compiler. If you want to see a really 
fast BASIC, try Microsoft's BASIC Com- 
piler. It also has the advantage that you 
can run your software on the interpreter 
first to remove all the bugs before compil- 
ing one time. 

4. His comments about string manip- 
ulations are true, except for one problem. 
There is a MID$ function to pull pieces of 
strings out, so that these can be convert- 
ed to real variables, but there is no easy 
way to reverse the process. That is, you 
cannot easily put real variables in the 
middle of a string. 



Just as a side note, there is a version of 
CP/M and CBASIC2 available for the 
TRS-80 Model I. I know ... I bought it. 
Only after this did I realize that there is no 
way you can effectively utilize it on this 
machine with 5-1/4 inch 35/40 track sin- 
gle density drives. CP/M and CBASIC2 re- 
quire eight-inch drives with their resul- 
tant capacity, or double density small 
drives. 

Charles Reeves, Jr. 
Union Carbide 
Oak Ridge, TN 

Response: 

I agree with Mr. Reeves's second point- 
Microsoft's BASIC-80 is very extensive. 
But it is also very expensive — almost 
three times as much as CBASIC2. I also 
agree with Mr. Reeves that BASIC-80, be- 
ing an interpreter, chews up a lot of com- 
puter memory. 

It is on point three that we differ. I must 
admit that when I went back to the 
benchmark programs in October 1977 
Kilobaud, CBASIC2 took a bath on the 
simple programs. However, by the time I 
got to program four, CBASIC2 had quite 
an advantage over my older Processor 
Technology Extended Cassette BASIC 
and over my Micropolis Disk BASIC. In 
using these benchmark tests, there is 
some problem in deciding when to start 
timing. Previously, I had started the stop- 
watch when I pressed RETURN after typ- 
ing RUN, but this is not valid with a CBA- 
SIC2 program, since after you enter 
"CRUN2 'filename' ", you must wait 
while the run time interpreter is loaded, 
the program is loaded and the execution 
begun. This time overhead is ridiculous 
for a short benchmark program, but it is 
negligible for one that will run for hours. 

Mr. Reeves's comments on Microsoft's 
BASIC Compiler are a little misleading. 
To write, run and debug your software on 
the interpreter and then compile it with 
the BASIC Compiler, you must have both 
sets of software, each of which costs over 
$300. Mr. Reeves needs almost $700 
worth of software to do what CBASIC2 
can handle for less than $100. 1 shall put 
up with these slight limitations unless 
Mr. Reeves or Microsoft is willing to send 
me a complimentary copy of BASIC-80 
and their BASIC Compiler! 

Mr. Reeves's fourth point is correct. I 
had not yet run into this problem. It can 
be programmed around by using the 
LEFT$ and RIGHT$ functions to split the 
original variable into two separate ones. 
Create the new string by concatenating 
the third string variable between these 
two strings. I agree this is a nuisance but 
it is not insurmountable. 

Mr. Reeves's "side note" only strength- 
ens my belief that "toy" microcomputers 
have no place in business. I use a SOL-20 
with a dual drive quad density Micropolis 
disk system. Each disk uses 77 tracks 
and can store 350K of data. For the same 
reason, I am typing this letter by hand— 



the inexpensive letter-quality printers 
cannot handle business applications and 
I cannot yet cost-justify a "professional" 
daisywheel! 

Bruce Evans, M.D. 

Pickering, Ontario 

Canada 



Business Applications 

Please accept my congratulations and 
best wishes for success in your new un- 
dertaking. Desktop Computing. 

Martin Klaver, writing the June Per- 
spectives, explained the problem beauti- 
fully — we need microcomputers for mi- 
cro applications — and we need to be able 
to learn to use them quickly. 

I have had an Apple II for about six 
months and have been trying to use it in 
connection with a real estate and related 
investment business. As a computer be- 
ginner, I'm having problems and I need 
help. 

Please sign me up for Desktop Com- 
puting. 

David S. Ailes 
Winter Park, FL 



No Longer Undocumented 

Edwin Freed's article about "secret" 
Z-80 codes (April 1981, p. 58) was both 
interesting and instructive. Although the 
additional codes do not promise to revo- 
lutionize Z-80 programming, they may 
indeed be handy at times. 

Tests run on my TRS-80 entirely con- 
firm the accuracy of Mr. Freed's state- 
ments. He does not, however, deal specif- 
ically with one group of codes: the four- 
byte codes starting with DDCB or FDCB. 
The 62 documented codes in this group 
perform rotations, shifts and bit opera- 
tions upon memory locations indicated 
by the IX or IY registers as offset by the 
value specified in the third byte of the 
code. The undocumented codes similarly 
use the IX or IY registers, with offest, as 
pointers to the memory locations affect- 
ed, but, with the exception of the BIT in- 
structions, they also load the results into 
a register. 

For example, the code DDCB05C8 will 
set bit 1 of the memory location whose 
address is five greater than the contents 
of the IX register and will also load the re- 
sulting value into the B register. For this 
operation, which would normally require 
two separate instructions, 1 use the mne- 
monic BSET UIX + 5), the letter B indi- 
cating the register loaded. 

The specific operations and the regis- 
ters loaded by these codes may be deter- 
mined readily by comparing the second 
and fourth bytes with the regular two- 
byte CB codes. Only in the case of the BIT 
operations is the indicated register left 
unloaded; thus the undocumented codes 
whose fourth byte is between 40 and 7F 
merely duplicate existing codes. 



196 Microcomputing, August 1981 



Even the RLO operation described by 
Freed is available: the code FDCB0937 
( ARLO (IY + 09)) rotates the byte indicat- 
ed by IY + 9 to the left, shifts a 1 into the 
low-order bit, and loads the result into 
the A register. Note that it would normal- 
ly take three instructions to accomplish 
this result. 

James Yo well Yelvington 
Stillwater, OK 



Calif orina Dreaming 

Here is one of those "I have never writ- 
ten a letter to the editor (all right, publish- 
er) before" letters. This time I cannot re- 
strain myself. 

I have just finished reading Wayne 
Green's comments in the June issue. As 
one of the old-time followers (more than 
five years), I am distressed to hear of the 
poor showing that this industry is accused 
of giving. Sure, I was at the Faire and saw 
all that you saw but I ask you — is it fair to 
judge our entire industry on the basis of 
this small coterie of 32,000 isolated 
individuals? 

No matter, I see further on that there is 
a serious article on the solid businesslike 
business of multitask systems. This will 
show them we have our act together! 
OOPS! As I peruse the lead photos of 
these two heavy duty and surely deadly 
serious computers I see screened right on 
the front panel that Action Computer En- 
terprise, Inc., believes that they are locat- 
ed in Pasadena, Califorina . . .CALI- 
FORINA? 

I hope that the article is great. I still 
can't read it through the tears in my eyes. 
Please, Lord, tell me that this is just the 
act of some misguided graphic artist re- 
touching the print for greater clarity. 

David Geo. Krauss 
Menlo Park, CA 

These are limited edition models. Act 
now while the supply lasts. Guaranteed 
to become a collector's item. — Ekiitors 






Passing the Buck 

Recently I faced a problem using a C. 
Itoh 25 cps Starwriter with a California 
Computer Systems (CCS) Centronics 
parallel interface, and the Apple PIE 
Word Processor by Programma. It seems 
the customary control-I 80N command 
that was needed couldn't be entered ex- 
cept as text in the program. 

To make a long story short, the driver 
program that was supplied with the CCS 
interface didn't cooperate with the C. Itoh 
printer. Talking to CCS put blame onto 
Apple PIE and C. Itoh; talking to Pro- 
gramma put blame onto CCS and C. Itoh; 
and, you guessed it, talking to C. Itoh put 
blame onto CCS and Apple PIE. 

The solution to this problem is so fun- 
damentally simple that it only needs nine 



bytes instead of the usual 256 bytes for a 
driver. It involves storing the accumula- 
tor into the appropriate data address for 
that slot ($C0n0, where n = slot + 8), load- 
ing the accumulator from the same ad- 
dress and then when the value is no long- 
er the same, to return for the next charac- 
ter. 

The program in Listing 1 is relocatable 
not only pagewise but wherever you have 
nine bytes to spare. 

You can even take this one step further 
by replacing the 5623 PROMs that the 
CCS board has with a pair of 2 1 12s (256 
byte by four bit RAM). Just remember 
which 5623 is the high order and which 
is the low order so if you replace them the 
board will function properly. 

A program like Apple PIE asks, by way 
of a SYSGEN Program, for the printer 
driver starting address. A slot number 
will automatically generate a SCnOO, 
where n = slot number. You may assign 
this to any address in memory if you de- 
sire. If you install the RAMs then you 
would just BLOAD the driver into the 
$CnOO address. If not, then the proverbi- 
al $300 is always there. 

Mark Johnson 

Schultz Systems, Inc. 

Barnegat, NJ 






A Different Approach 

I have a few comments to add to the 
"North Star Quiz" which was in the June 
issue. I approached the problem of the ex- 
clamation point and PRINT commands 
differently, by modifying the command 
table in the BASIC itself. By changing the 
code for the exclamation point command 
from 146 to 130, when new programs are 
typed both the exclamation point and 
PRINT are stored as the same code and 
will therefore be listed as PRINT. How- 
ever, to properly list a previous program 
which used the original 146 code, it has 
to remain in the command table un- 
changed also. For this patch to work 
properly, the PRINT must be first, the 
changed exclamation point second and 
the unchanged exclamation point last. 
They don't have to be the first three en- 
tries in the table, nor do they have to be 
adjacent, but they should be in this 
order. Since other data follows this table 
its size can't be changed. 

I gained the extra two bytes by reduc- 
ing SQRT to SQR and FREE to FRE. 
Looking over the table again I see that a 
better possibility would be to delete the 
square bracket. The only purpose of this 
in the table is to automatically convert an 
open bracket to an open parenthesis. In- 
cidentally, Mr. Prisco left the FREE com- 
mand out of his list; it is 216 decimal or 
D8 hex. 

The command table starts at 3B65 hex 
or 15205 decimal in the single-density re- 
lease four version. I don't know about the 
other versions, but it is easy to find by us- 



]PRINTCHR$(9>; 


"80N" 






]CALL-151 










•300L 












0300- 


8D 


A0 


CO 


STA 


SC0A0 


0303- 


AD 


A0 


CO 


LDA 


SC0A0 


0306- 


30 


FB 




BMI 


$0303 


0308- 


60 






RTS 




0309- 


00 






BRK 




030A- 


00 






BRK 




030B- 


00 






BRK 




30C- 


00 






BRK 




30D- 


00 






BRK 




030E- 


00 






BRK 




030F- 


00 






BRK 




0310- 


00 






BRK 




0311- 


00 






BRK 




0312- 


00 






BRK 




0313- 


00 






BRK 




03K- 


00 






BRK 




0315- 


00 






BRK 




0316- 


00 






BRK 




0317- 


00 






BRK 




0318- 


00 






BRK 




•D4F2G 













]C0A0 IS THE APPROPRIATE DATA ADDRESS FOR SLOT # 2 



Listing 1. 



ing an ASCII dump routine such as the 
DA command in the North Star Monitor 
program. The code byte precedes each 
string. 

About the only problem with this 
change is that an exclamation point in a 
REMark is also expanded to PRINT. This 
doesn't affect the running of the pro- 
gram, but it sure lists funny. Actually, 
Mr. Prisco's programs would do the same 
thing, but they could be rewritten easily 
to check for the REM code to ignore the 
rest of the line. 

Another change that I made to the 
command table was to change EXAM 
and FILL to PEEK and POKE. There is no 
real advantage to this, but it gives some 
strange effects when listing a program 
that was entered without this patch. For 
example, the phrase FOR EXAMPLE 
comes out FOR PEEKPLE. 



Larry Hudson 
Ventura, CA 




"> 



3D 
3D 




00 
00 
00 



oo 
no 
□ o 

00 

DO 

nn 



OQDO 
np /uU-^ 

OD 
DD 
DO 



©lite 



.en 



nn 



DQDD 

Doaa 

ODDD 

nnnn 



"If Superman isn't around, we'll be meeting our maker 
in 4.956 seconds." 



Microcomputing, August 1981 197 



NEW PRODUCTS 

Xerox Desktop Computer 

Talking Telephone Terminal 
Micro Security Cabinet 
Apple/Turtle Interface 



Edited by Linda Stephenson 



Desktop Computer 
and Word Processing 
System 

A 64K desktop workstation 
that can be used as a word pro- 
cessing system, a business 
computer or both is available 
from Xerox Corporation, Office 
Products Division, 1341 West 
Mockingbird Lane, Dallas, TX 
75247. The Xerox 820 can also 
be connected to the 
company's Ethernet local area 
communications network, 
which links different kinds of 
office equipment for high- 
speed exchange of informa- 
tion. As a word processor, the 
820 is designed for organiza- 
tions needing low-cost display 
systems. As a desktop comput- 
er, it is intended for small 
businesses and for profession- 
als and managers in larger 
organizations. Appropriate 
software tailors the equipment 
for either function. 



The system's standard disk 
storage has a capacity of about 
45 pages of text. A larger disk 
unit, with a storage capacity of 
about 140 pages, is available as 
an option. The printer is a 
daisywheel Diablo 630, which 
prints bidirectionally at up to 
40 characters per second. 
Xerox will provide the indus- 
try-compatible operating 
system software for the 820. 
Price of the desktop computer 
version, including display 
screen, keyboard and standard 
disk storage, is $2995. As a 
word processing system, with 
the optional 40-cps daisywheel 
printer, price is $5895. Soft- 
ware is priced separately. 
Reader Service number 489. 



Intelligent Telephone 
Controller 

The SLC-II is a serial line 
controller that combines 




Xerox 820 information processor. 




A telephone-based terminal operator from Digital Pathways. 



microprocessor intelligence 
with voice synthesis capabili- 
ty. The SLC-II can automati- 
cally dial phone lines and talk 
in its electronically synthe- 
sized voice. Its vocabulary in- 
cludes more than 300 words, 
the alphabet and numbers. 
The SLC-II will spell what it 
can't say. No software changes 
to the host computer's 
operating system are needed. 
The SLC-II connects between 
any computer and terminal to 
monitor the flow of messages. 
It can then be taught to initiate 
voice messages at specific time 
intervals — or upon recognition 
of certain messages moving 
from computer to terminal. 
The SLC-II can also listen and 
respond to incoming phone 
messages that originate at a 
remote terminal or are gener- 
ated by a telephone keypad. 

The SLC-II features auto- 
matic time and date entry with 
a day/month/year calendar. It 
also comes with built-in power 
backup via rechargeable bat- 
teries, an auto-dial/auto- 
answer modem, and 16K, 32K 
or 80K RAM. Priced at $1975. 
Reader Service number 486. 

Digital Pathways, Inc.. 1260 
L'Avenida, Mountain View, 
CA 94043. 



Microcomputer 
System Security 
Cabinet 

An attractive and practical 
microcomputer cabinet is 
available from Instructional 
Development Systems, 2927 
Virginia Beach Blvd., Virginia 
Beach. VA 23452. Compatible 
systems include Apple II, 
Atari, Texas Instruments 99/4, 
Ohio Scientific, Sorcerer and 
other modular systems. The 
wood door provides maximum 
equipment security with two 
solid brass locks and a full 
piano hinge; the door opens to 
serve as a work table. The 
microprocessor and disk drive 
units slide out on tray rollers, 
providing easy access to com- 
ponents. Adequate space is 
provided for most 13-inch 
televisions or monitors: 
monitors are angled down for 
maximum screen visibility. 
The design of the cabinet 
assures a distance of approxi- 
mately 24 inches from the 
user's eyes to the television 
screen, reducing the danger of 
radiation exposure, eye strain 
and fatigue. 

Two minidisk storage com- 
partments hold as many as 100 






198 Microcomputing, August 1981 



LOWEST PRICE - BEST QUALITY 



NORTH STAR 




North Star Horizon 2 

2-5 Va Disk Drives 
32K Double Den 
Factory assem. & tested 
Factory guaranteed 
List $3695 



only 

POWERFUL NORTH STAR 
SUPERB FOR BUSINESS 

FACTORY ASSEMBLED & TESTED LIST 

HORIZON-2-64K-DOUBLE DEN $4195 

HORIZON-2-32K-QUAD DENSITY $3995 

HORIZON-2-64K-QUAD $4495 

HORIZON RAM ASSM 1 6K = $279 

HORIZON RAM ASSM 48K ■ $679 

HORIZON DISK DRIVE SALE 

DOUB DEN SAVE! 

NORTH STAR HARD DISK 18 Mb $5375 

NORTH STAR TIME SHARING MULTI-USER 



$2697 

BASIC FREE 
& SCIENCE 



ONLY 
$3062 
$2916 
$3281 
32K=$479 
64K - $879 

$ 445 

$3923 

CALL 



SUPERBRAIN 

ZENITH 





SUPERBRAIN QD 64K 

List $3995 only $2995 




Z-89 48K 

List $2895 only $2299 



TERMINALS Z-19 $725 

INTERTUBEIII om y $725 

DYNABYTE COMPUTER— SAVE— PHONE 

EPSON MX-80— PHONE 
^ ANADEX 9501 $1349 

NEC PRINTER $2639 
TRACTOR, 

THIMBLE, 

RIBBON 

DIP-81 $395 

TEC LETTER QUAL $1599 





InterSystems 

ITHACA INTERSYSTEMS 2A 

Z-80A CPU 4 MHz 
64K Dynamic RAM 
Front panel 
V I/O — with interrupts 
FDCII Disk Controller 
20 slot motherboard 

CALL FOR PRICE- 
TOO LOW TO ADVERTISE! 

PASCAUZ + THE FASTEST PASCAL $375 

Z-8000 & CACHE BIOS— POWERFUL— PHONE 

8086 16 BIT CPU & SUPPORT CARD SEATTLE $695 

CALIFORNIA COMPUTER 221 0A ONLY $1795 

MORROW 8" DISK 

DISCUS 2D + CP/M® 600K ONLY $929 
DISCUS 2 + 2 + CP/M® 1.2 MEGA B. $1240 

ADD DRIVES 2D = $650 2+2= $975 
2D-DUAL + CP/M® ONLY $1540 

FREE MBASIC FROM MORROW!! 




MORROW HARD DISK 

26,000,000 BYTES!! 

LIST $4995 ONLY $3919 

CP/M® IS INCLUDED! 



SAVE ON MEMORY AND PROGRAMS 



SYSTEMS MEMORY 64K A & T 4mHz 

$590 

SYSTEM MEMORY 64K BANK SELECT 

$740 

ITHACA MEMORY 8/1 6-bit 64K $845 

SEATTLE MEMORY 8/1 6 BIT 1 6K $249 

SSM KITS Z-80 CPU $221 

VIDEO BRDV83 4Mhz $412 

ANADEX PRINTER DP-9500-1 $1349 

CAT NOVATION MODEM S 1 69 

ECONORAM2A8KASSM $179 

NSSE 1-22 A P01 TERRIFIC PROGRAMS 

ONLY $10. EACH 
NORTHWORD $329 MAILMAN $246 
INFOMAN $41 1 



WORDSTAR 



$315 



SPECTRUM $269 

COMPUPRO SAVE 

EZ-CODER Translates English to BASIC 

$71 
ECOSOFT FULL ACCOUNTING PKG 

$355 
BOX OF DISKETTES $29 

SECRETARY WORD PROCESSOR 

The Best! $99 
GOFAST NORTH STAR BASIC 
OPTIMIZER— FAST $71 

Which Computers are BEST? 
BROCHURE FREE 

North Star Documentation refundable 

w/HRZ $35 



TARBELL COMPUTER-PHONE 

AMERICAN SQUARE COMPUTERS BEATS ADV. PRICES 



square 

American [||] Computers 

919-889-4577 KIVETT DR. JAMESTOWN N.C. 27282 919-883-1105 



^56 






(D 



CP/M is a registered trademark of Digital Research, Inc. 



M 



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DISCOUNT 



Stock Computer Paper & Labels 
Over 50 Items in Stock 



ITEMS IN STOCK 


Custom To Your Needs 


Stock Forms Blank or Green Bar 


Invoices 


Statements 


Shippers 


Index Cards 


Custom Checks 


Pressure sensitive labels all sizes 


Custom Continuous Envelopes 


Continuous #10 envelopes 


& Letter Heads 


Continuous Blank Letter Heads 


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Spacing charts & layout sheets 




Forms rulers 


Quantities Of 1000 Or More 



} 




Send Inquiries To: 

WHITE RIVER PRODUCTS ^284 

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Are you playing 

with a full deck? 



5> 




If you are holding an AIM, SYM, KIM, PET or OSI, then 
you need our 1981 Product Guide to fill your hand. 

The Computerist deals only superior products: 

Dram Plus — RAM, EPROM, Programmer and I/O. 
Video Plus — Instant video up to 132 by 30, plus 

communication and keyboard ports. 
Mother Plus — Supports multi-board expansion, 

cassette control and more. 
Proto Plus — Add custom circuits easily. 
Power Plus — Triple voltage supply. 

Why stand when you can take a guaranteed hit? 

For the best deal in town, 
write or call for our free 1981 Product Guide 



^336 



l/LrJ.^ 34 Ch e ,m sford St., Chelmsford, MA 01824 

^ (617)256-3649 



®(*M]s>taTCia[i§tf 



® 




A wood storage cabinet from Instructional Development 
Systems will secure modular micro systems. 



disks, or one storage compart- 
ment can be used to house a 
small line printer. The cabinet 
is solid wood with a formica 
veneer. Convection venting is 
included to cool system com- 
ponents. The cabinet comes 
fully assembled and ready to 
use. Priced at $275. Reader 
Service number 485. 



Letter-Quality 
Printer 

The Sprint 9 letter-quality 
daisywheel printer, from Data 
Wholesale Corp., 700 Whitney 
St., San Leandro, CA 94577, 
now offers an improved car- 
riage drive mechanism. The 
micro-drive Kevlar belt 
enhances print quality and 
registration, and also makes 
steel carriage cables, pulleys 
and excessive service ad- 
justments obsolete. The 
Sprint 9 has fewer parts, mak- 
ing it easier to service than 
previous Sprint products. The 
top cover has been totally 
redesigned for easier carriage 
assembly access. The printer 



also features acoustic sound 
reduction, an internal power 
supply and new quick-load rib- 
bons. 

Sprint 9 is available with two 
different RO front panel con- 
figurations, limited or com- 
plete front panels, at either 45 
or 55 cps. The Sprint 9/45 is 
$2455 ($100 less for a limited 
front panel): the 9/55 is $2555 
($100 less for limited front 
panel). Reader Service num- 
ber 484. 



Interface with a 
Turtle 

Terrapin, Inc.. 678 
Massachusetts Ave., #205. 
Cambridge, MA 02139. now 
has a smart Terrapin-Apple in- 
terface for its robot, the Turtle. 
The interface lets the user con- 
trol the Turtle from a high- 
level language (BASIC, Pascal. 
Logo) via simple I/O state- 
ments. It can be used at home 
or in the classroom for 
teaching, learning or just hav- 
ing fun. The smart interface 
includes a parallel port, a 







Sprint 9 letter-quality printer from Data Wholesale. 



200 Microcomputing, August 1981 




separate regulated current- 
limited power supply and in- 
terface software. The parallel 
port I/O card contains the in- 
terface software in ROM, and 
plugs into one of the Apple's 
peripheral interface connec- 
tors. The program in ROM ini- 
tializes the I/O port, generates 
the appropriate bit pattern for 
a specific command, compares 
this with the previous com- 
mand byte to determine which 
bits must be left on. and writes 
to the appropriate output port 
location. The interface soft- 
ware allows Turtle control 
commands to be sent directly 
to the Turtle. The assembled 
Terrapin Turtle costs $599.95; 
kits are $399.95. Interfaces 
are $199.95. Reader Service 
number 493. 



Biofeedback 

The Biocom is a new 
peripheral from Total Digital 
Engineering. 210 Daniel Web- 
ster Highway. S. Nashua, NH 
03060. Biocom measures your 
galvanic skin response (GSR) 
using two Velcro wrappers for 
your fingers (or one from each 
person at the end of a circle of 



people holding hands). The 
user selects sample rate, sen- 
sitivity and how the readings 
are to be processed and 
presented. The readings are 
transmitted to your microcom- 
puter, where, with the ap- 
propriate software, the 
readings will produce a GSR 
plot or act as a relaxation 
trainer, a computerized Ouija, 
a lie detector or a personal 
growth system. 

Biocom is easily tied into 
your computer via an asyn- 
chronous RS-232 port. Soft- 
ware is supplied as BASIC 
listings, annotated to point out 
differences in the interpreters 
of different microcomputers. 
You can also buy software on 
cassette or diskette for $15. 
The Biocom, with manual, list- 
ings and personal growth 
booklet, is $125. Reader Ser- 
vice number 492. 



Design Tool 

The Pencil Box logic 
designer is a portable bread- 
boarding instrument for de- 
signing logic circuits and in- 
cludes an I/O port for micro- 
computer experiments. The 







I 



The Biocom biofeedback peripheral from Total Digital Engi- 
neering. 



with 32 pages of 
continuous 
business forms for 
small computer 
systems 



Send today for our NEW full color 32 
page catalog with programming guides, 
prices and order forms for continuous 
checks, invoices, statements, envelopes, 
stock paper and labels. 

• Quality products at low prices 

• Available in small quantities 

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• Convenient TOLL-FREE 



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Mass. residents 1+800-922-8560 
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A division of New England Business Service, Inc 




^See List of Advertisers on page 194 



Microcomputing, August 1981 201 



IT'S ABOUT TIME! 



SUPERCLOCK II™ 



A COMPLETE 
CLOCK/CALENDAR 
SYSTEM FOR THE 

APPLE II. 



FEATURES: 

• Timing from milliseconds to 99 years 

• 12/24 Hour formats plus day of week 

• Does not use C800-CFFF address space 

• Automatic dating of files stored on disk 

• Automatic updating of PASCAL'S Filer 

• Up to four software controlled interrupts 

• Full battery operation for up to 10 years 





^^1 JSfojjjJIa ^Hft ^IfMiHfif 'jflj[tfifr 


"; • "■'■' i 




H 


L 


|5MC V/ I 

1 1 itto m'^i m 




...... .......::jlE 






HNMIHMIir 



1 



> 






SUPERCLOCK II COMPLETE SYSTEM $159 




TIME-CLOCK II program automatically keeps track of the 
time you spend on your computer for each job, client, pro- 
gram, etc. Then prints out a detailed report. Requires 
SUPERCLOCK II, Applesoft, and disk $30 



west side electronics 

PO. Box 636D, Chatsworth, CA 91311 Phone (213) 884 4794 

All orders • add $3 50 for postage, insurance, and handling ($7.00 

outside Continental USA) California residents add 6% sales tax 

A 3% surcharge will be added to all credit card orders 

Apple. Apple II. and Applesoft are trademarks of Apple Computer Inc 



MODEL III DISK 
DIRECTORY PROGRAM 



Catalogue your Diskettes with this easy 
to use Catalogue program for Model III 
Disk systems. Can run on as little as a 
32K 1 Drive system. Help you keep 
track of ALL of your programs. 

ONLY $19.95 



MODEL III SPEED UP! 



Load in the 500 Baud system tapes in 
1/3 the time with copy III. This utility 
will read in your 500 baud system tapes, 
and then write them out at 1 500 baud. 
This gives you backup protection as 
well as speeding up your tapes. A must 
for all Model III Cassette users! 

ONLY $14.95 



VrSA 



D.T. Enterprises ^124 
171 Hawkins Road 
Cenrereach, New York 1 1 720 

(516) 981-8568 (Voice) 
(516) 588-5836 (Doto) 
MNET-70331 , 1 05 NYS res. odd oppr. fox 

Dealers Inquiries Welcome Add $2.00 S & H 




The Pencil Box from E&L Instruments. 



Pencil Box incorporates major 
design needs in a molded 
plastic case with an integral 
hinged cover. It features a 
variable clock, two pulsers, 
eight LED readouts which also 
serve as a latched output port, 
eight logic-level switches 
which also serve as an input 
port and E&L SK- 10 solderless 
breadboarding socket. Power 
is supplied by four 1.5 V bat- 
teries or an optional ac 
adapter. A Zener diode re- 
duces the input voltage to 5 V 
for standard TTL work. The 
Pencil Box, assembled, is 
priced at $99.50: kit is $75. 

E&L Instruments, Inc.. 61 
First St., Derby, CT 06418. 
Reader Service number 491. 



RAM Card for Apple 
II 

Computer Stop, 2545 W. 
237th St., Suite L, Torrance, 
CA 90505, is offering the 
CS16K RAM card to increase 
Apple II memory. With 48K of 
RAM already in place, this 
new card increases capacity 



to 64K. This RAM is comput- 
er-designed, using the short- 
est distance between points 
and laying heavy traces that 
improve overall reliability. It 
is compatible with Pascal, 
CP/M, DOS 3.3, COBOL, FOR- 
TRAN, VisiCalc, PILOT. Inte- 
ger BASIC, Applesoft BASIC 
and other software currently 
used with Apple II. This addi- 
tional 16K RAM lets you run 
the 56K CP/M operating sys- 
tem, increases buffer storage 
for word processing and Visi- 
Calc or other calculation pro- 
grams, and lets you run with 
FORTRAN and other high-lev- 
el programming languages. It 
is priced at $195. Reader ser- 
vice number 499. 



Z-80 Processor 
Board 

The CPC-2810 Z-80 proces- 
sor board is now being offered 
by Systems Group, a division 
of Measurement Systems and 
Controls, Inc., 1601 Orange- 
wood, Orange, CA 92668. The 
board is designed specifically 



OI0O8) 



I6K RAM 

by computer stop . 



II 



Computer Stops CS16K RAM card. 



202 Microcomputing, August 1981 



COMPUTER STOP 



^105 



2545 W. 237 St. Torrance, CA. 90505 



ORDER BY PHONE 

MON.— SAT. 

10-6 

(213) 539-7670 PST 
TELEX: 678401 TAB IRIN 



LOWEST PRICES IN THE WEST.NORTH. SOUTH & EAST 




Tcippkz computer 

r Sales and Sen/ice 

APPLE /// OPTION A: 3850 

APPLE /// 96K 

Information Analyst Package 

12" B/W Monitor 
APPLE ///OPTION B: 4350 

SAME AS OPTION A PLUS: 

DISK II for APPLE /// 
APPLE /// OPTION C: 4800 

SAME AS OPTION A PLUS: 

DISK II FOR APPLE /// 

SILENTYPE Thermal Printer 



APPLE HARDWARE 

Parallel Printer Interface Card 160 

Communications Card 195 

High Speed Serial Interface 175 

Pascal Language System 425 

Centronics Printer Interface 185 

Applesoft Firmware Card 160 

Integer Firmware Card 160 

Disk ][ with Controller DOS 3.3 529 

Disk ][ only 475 

Graphics Tablet 625 

OTHER HARDWARE 

Alf Music Synthesizer (3 Voice) 245 

9 voice 1 75 

ABT Numeric Keypad 119 

Micromodem ][ 295 

Apple Clock 245 

Rom Plus with Keyboard Filter 175 

lntrol/X-10 System 250 

Romwriter 150 

Double Vision 80 x 24 Video Interface 295 

CCS Arithmetic Processor 399 

CCS Parallel Interface 119 

16K Ram Card 145 

Microworks DS-65 Digisector 339 

SVA 8 inch Disk Controller 335 

Sup-R-Mod 30 

CCS Synchronous Serial Interface 159 

CCS Asynchronous Serial Interface 159 

Corvus 10 Meg. Hard Disk 4395 

Corvus Constellation 595 

MISCELLANEOUS/SUPPLIES 

16K RAM (200-250 NS) 49 

Verbatium Datalife Diskette (Box of 10) 30 

Dysan Diskettes (Box of 5) 22 

Apple Diskettes (Box of 10) 45 

Verbatim Diskette Boxes (Holds 50 Disks) 18 

Silentype Paper (Box of 10 rolls) 40 




APPLE ][ Plus 

16K $1075 

48K $1193 

Disk][Drive..$529 

with Controller & Dos. 3.3 

PASCAL SYSTEM 

$425 

Z-80 Softcard 

$299 



MONITORS/DISPLAYS 

Leedex Video 100 12" 140 

Sanyo 9" Monitor 195 

KG-12C Green Phos. Monitor 275 

Sanyo 12" Green Phosphor. Monitor 275 

NEC 12" Green Phosphor. Monitor 275 

Sanyo 12" B/W Monitor 250 

PRINTERS 

Apple Silentype with Interface 525 

IDS445 (Paper Tiger) with Graphics 695 

IDS460 with Graphics 1099 

IDS560 with Graphics 1295 

Centronics 737 895 

NEC Spinwriter (RO, Serial) 2650 

SOFTWARE 

The Controller 525 

Apple Post (Mailing List Program) 40 

Easy writer Professional System 195 

Apple Pie 2.0 95 

DB Master Data Management 150 

The Cashier 210 

Apple Writer 65 

Visicalc 1 25 

CCA Data Management System 90 

Full Screen Mapping for CCA DMS 59 

Pascal Interactive Terminal Software (PITS) 29 

Basic Interactive Terminal Software (BITS) 29 

Data Capture 29 

Data Factory DMS 95 

Apple Plot 55 

Apple Pilot 120 

Magic Wand Word Processor (Needs Z-80 Softcard) 345 

Dow Jones Portfolio Evaluator 45 

Fortran 1 40 



ORDERING INFORMATION: Phone orders invited using VISA, MASTERCARD or bank wire transfers. VISA & MC credit card service charge of 2%. Mail order may send charge 
card number (include expiration date), cashier's check, money order or personal check (allow 10 business days to clear). Please include a telephone number with all orders. 
Foreign orders (excluding Military PO's) add 5% for shipping. All funds must be in U.S. dollars (letters of credit permitted). Shipping, handling and insurance in U.S. add 2% 
(minimum $4. OX)). California residents add 6% sales tax. Our low margins prohibit us to send COD or on purchase orders or open account (please send for written quotation). All 
equipment is subject to price change and availability. Equipment is new and complete with the manufacturer warranty. We do not guarantee merchantibility of products sold. All 
returned equipment is subject to a 15% restocking fee. We ship most orders within 2 days 

RETAIL STORE PRICES MAY DIFFER FROM MAIL ORDER PRICES. 



WE ARE A MEMBER OF THE CHAMBER OF COMMERCE. 



PLEASE SEND ORDERS TO: 



COMPUTER STOP, 2545 W. 237 St., TORRANCE, CA 90505 



t^See List of Advertisers on page 194 



Microcomputing, August 1981 203 




Systems Group Z-80 processor board. 



for the S- 100 bus, and is com- 
patible with single-user, mul- 
ti-user or networking sys- 
tems. It features two or four 
serial I/O channels, software- 
selectable baud rates, two 
parallel I/O channels and 
eight vectorized, prioritized 
interrupts. The price is $495. 
Reader service number 498. 



Increase H/Z-89 
Storage to 7.6 
Megabytes 

A new double-density disk 
controller for the Heath/Ze- 
nith-89 computer supports up 
to four eight-inch disk drives 
and four five-inch drives. 
These supplement the three 
five-inch drives supported by 
the existing Heath/Zenith 
controller. The new controller 
increases on-line access to 
7.6M. It can handle any com- 
bination of industry -standard 
eight-inch drives and five- 
inch 40-track or 80-track 
drives in either single- or dou- 
ble-sided versions. The con- 
troller is priced at $595, in- 
cluding CP/M 2.2 on either 
five-inch or eight-inch media. 



Magnolia Microsystems, 
Inc., 2812 Thorndyke Ave.. 
West. Seattle, WA 98199. 
Reader Service number 497. 



Disk Storage for 
TRS-80 Model m 

The Disk III, offered by VR 
Data, 777 Henderson Blvd., 
N-6, Folcroft Industrial Park, 
Folcroft, PA 19032, is a 5-1/4 
inch disk storage subsystem 
for the Radio Shack TRS-80 
Model III computer. It is fully 
compatible with the Model III 
hardware and software. The 
Disk III is calibrated, aligned, 
tested and burned-in prior to 
shipping. It can be installed by 
VR Data, or can be easily in- 




VR Data's Disk III. 




minimum 




Archtues /// word processor/computer. 



stalled by any mechanically 
inclined person with simple 
hand tools. The Disk III basic 
unit consists of controller, 
power supply, mounting 
bracket, one 40-track (6 ms) 
disk drive and associated ca- 
bling. Price is $599. Reader 
Service number 495. 



Static 64K RAM Uses 
100 ns Chip 

Seattle Computer Products, 
1114 Industry Drive, Seattle, 
WA 98188, recently an- 
nounced their SCP- 1 10, a 64K 
IEEE S-100 memory card. It 
uses the 100 ns Intel 2167 16K 
static chip. The new chip 
allows memory management 
functions of offset and protec- 
tion to be performed with the 
firms 8 MHz 8086 CPU with- 
out a wait state. The card per- 
forms both eight-bit and 16-bit 
transfers, switching automat- 
ically. The chips are used in a 
power-down mode to mini- 
mize current. Power require- 
ment for an active board is 1.6 



A at 8 V, while an inactive card 
uses 0.8 A. The card uses 
24-bit addressing; the upper 
eight can be disabled. Price is 
$1295. Reader Service num- 
ber 487. 



More Available 

Memory 

The Archives III word pro- 
cessor/computer offers greater 
storage capacity than previous 
models. The Archives III 
features a Tandon double- 
sided disk drive and a Seagate 
5M 5- 1/4 inch Winchester disk 
drive. Total storage will be 
5.75M. The unit is priced at 
$8500. 

Archives Inc., 404 West 
35th St., Davenport. IA 52806. 
Reader Service number 494. 



Touch-Sensitive Add- 
On for Lear Siegler 
Terminal 

Interaction Systems, Inc., 
24 Munroe St., Newtonville, 



r '©? 



ll II ,(D 'jt IL JP"*r m ' L J^Tl 



S»- 




Double-density disk controller from Magnolia Microsystems. 



Static RAM card from Seattle Computer Products. 



204 Microcomputing, August 1981 







Interaction Systems' TK-242 touch-sensitive add-on kit for the 
ADM-42. 



MA 02 160, is offering its Model 
TK-242 touch-sensitive add-on 
kit, designed for use with the 
Lear Siegler ADM-42 CRT ter- 
minal. The kit provides the 
video display terminal with a 
human interface that is easy to 
use. The touch-sensitive 
feature lets the terminal re- 
spond to the touch of the finger 
on data displayed on the CRT 
screen. The kit consists of a 
glass touch-sensitive faceplate 
that overlays the terminal's 
CRT monitor, an electronics 
board and mounting bracket 
which fit inside the CRT 
monitor housing and intercon- 
necting cables and mounting 



clamps. The price is $995. 
Reader Service number 496. 



Apple-Compatible 
Printer 

IMP2-Apple, a low-cost im- 
pact printer designed to oper- 
ate with Apple microcom- 
puters, is being offered by Ax- 
iom Corporation, 5932 San 
Fernando Road, Glendale, CA 
91202. IMP2-Apple is 
equipped with both friction 
and tractor feed. This versatile 
printer enhances the Apple's 
capabilities by providing extra 
features, such as lowercase 




Axiom IMP2-Apple printer 



f 




"a 



SPECIAL DELIVERY 



WORDPROCESSING 

- POWER - 

for the TRS-80® 

"...If you're presently looking for a mailing list proc- 
essor, this represents the current state of the art." 

80 MICROCOMPUTING - 80 REVIEWS - JULY 1980 

MAILFORM is data entry at its best, just fill in 
the form! FAST, EASY to use functions include: